The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 779b9955f64327c339a16f68055af98252fd3315
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025012002-spent-fervor-ada9@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 779b9955f64327c339a16f68055af98252fd3315 Mon Sep 17 00:00:00 2001
From: Yosry Ahmed <yosryahmed(a)google.com>
Date: Mon, 13 Jan 2025 21:44:58 +0000
Subject: [PATCH] mm: zswap: move allocations during CPU init outside the lock
In zswap_cpu_comp_prepare(), allocations are made and assigned to various
members of acomp_ctx under acomp_ctx->mutex. However, allocations may
recurse into zswap through reclaim, trying to acquire the same mutex and
deadlocking.
Move the allocations before the mutex critical section. Only the
initialization of acomp_ctx needs to be done with the mutex held.
Link: https://lkml.kernel.org/r/20250113214458.2123410-1-yosryahmed@google.com
Fixes: 12dcb0ef5406 ("mm: zswap: properly synchronize freeing resources during CPU hotunplug")
Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com>
Reviewed-by: Chengming Zhou <chengming.zhou(a)linux.dev>
Cc: Johannes Weiner <hannes(a)cmpxchg.org>
Cc: Nhat Pham <nphamcs(a)gmail.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
diff --git a/mm/zswap.c b/mm/zswap.c
index 30f5a27a6862..b84c20d889b1 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -820,15 +820,15 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
{
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
- struct crypto_acomp *acomp;
- struct acomp_req *req;
+ struct crypto_acomp *acomp = NULL;
+ struct acomp_req *req = NULL;
+ u8 *buffer = NULL;
int ret;
- mutex_lock(&acomp_ctx->mutex);
- acomp_ctx->buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
- if (!acomp_ctx->buffer) {
+ buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
+ if (!buffer) {
ret = -ENOMEM;
- goto buffer_fail;
+ goto fail;
}
acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
@@ -836,21 +836,25 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
pr_err("could not alloc crypto acomp %s : %ld\n",
pool->tfm_name, PTR_ERR(acomp));
ret = PTR_ERR(acomp);
- goto acomp_fail;
+ goto fail;
}
- acomp_ctx->acomp = acomp;
- acomp_ctx->is_sleepable = acomp_is_async(acomp);
- req = acomp_request_alloc(acomp_ctx->acomp);
+ req = acomp_request_alloc(acomp);
if (!req) {
pr_err("could not alloc crypto acomp_request %s\n",
pool->tfm_name);
ret = -ENOMEM;
- goto req_fail;
+ goto fail;
}
- acomp_ctx->req = req;
+ /*
+ * Only hold the mutex after completing allocations, otherwise we may
+ * recurse into zswap through reclaim and attempt to hold the mutex
+ * again resulting in a deadlock.
+ */
+ mutex_lock(&acomp_ctx->mutex);
crypto_init_wait(&acomp_ctx->wait);
+
/*
* if the backend of acomp is async zip, crypto_req_done() will wakeup
* crypto_wait_req(); if the backend of acomp is scomp, the callback
@@ -859,15 +863,17 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_req_done, &acomp_ctx->wait);
+ acomp_ctx->buffer = buffer;
+ acomp_ctx->acomp = acomp;
+ acomp_ctx->is_sleepable = acomp_is_async(acomp);
+ acomp_ctx->req = req;
mutex_unlock(&acomp_ctx->mutex);
return 0;
-req_fail:
- crypto_free_acomp(acomp_ctx->acomp);
-acomp_fail:
- kfree(acomp_ctx->buffer);
-buffer_fail:
- mutex_unlock(&acomp_ctx->mutex);
+fail:
+ if (acomp)
+ crypto_free_acomp(acomp);
+ kfree(buffer);
return ret;
}
The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 779b9955f64327c339a16f68055af98252fd3315
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025012002-overstep-numbness-cf60@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 779b9955f64327c339a16f68055af98252fd3315 Mon Sep 17 00:00:00 2001
From: Yosry Ahmed <yosryahmed(a)google.com>
Date: Mon, 13 Jan 2025 21:44:58 +0000
Subject: [PATCH] mm: zswap: move allocations during CPU init outside the lock
In zswap_cpu_comp_prepare(), allocations are made and assigned to various
members of acomp_ctx under acomp_ctx->mutex. However, allocations may
recurse into zswap through reclaim, trying to acquire the same mutex and
deadlocking.
Move the allocations before the mutex critical section. Only the
initialization of acomp_ctx needs to be done with the mutex held.
Link: https://lkml.kernel.org/r/20250113214458.2123410-1-yosryahmed@google.com
Fixes: 12dcb0ef5406 ("mm: zswap: properly synchronize freeing resources during CPU hotunplug")
Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com>
Reviewed-by: Chengming Zhou <chengming.zhou(a)linux.dev>
Cc: Johannes Weiner <hannes(a)cmpxchg.org>
Cc: Nhat Pham <nphamcs(a)gmail.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
diff --git a/mm/zswap.c b/mm/zswap.c
index 30f5a27a6862..b84c20d889b1 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -820,15 +820,15 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
{
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
- struct crypto_acomp *acomp;
- struct acomp_req *req;
+ struct crypto_acomp *acomp = NULL;
+ struct acomp_req *req = NULL;
+ u8 *buffer = NULL;
int ret;
- mutex_lock(&acomp_ctx->mutex);
- acomp_ctx->buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
- if (!acomp_ctx->buffer) {
+ buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
+ if (!buffer) {
ret = -ENOMEM;
- goto buffer_fail;
+ goto fail;
}
acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
@@ -836,21 +836,25 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
pr_err("could not alloc crypto acomp %s : %ld\n",
pool->tfm_name, PTR_ERR(acomp));
ret = PTR_ERR(acomp);
- goto acomp_fail;
+ goto fail;
}
- acomp_ctx->acomp = acomp;
- acomp_ctx->is_sleepable = acomp_is_async(acomp);
- req = acomp_request_alloc(acomp_ctx->acomp);
+ req = acomp_request_alloc(acomp);
if (!req) {
pr_err("could not alloc crypto acomp_request %s\n",
pool->tfm_name);
ret = -ENOMEM;
- goto req_fail;
+ goto fail;
}
- acomp_ctx->req = req;
+ /*
+ * Only hold the mutex after completing allocations, otherwise we may
+ * recurse into zswap through reclaim and attempt to hold the mutex
+ * again resulting in a deadlock.
+ */
+ mutex_lock(&acomp_ctx->mutex);
crypto_init_wait(&acomp_ctx->wait);
+
/*
* if the backend of acomp is async zip, crypto_req_done() will wakeup
* crypto_wait_req(); if the backend of acomp is scomp, the callback
@@ -859,15 +863,17 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_req_done, &acomp_ctx->wait);
+ acomp_ctx->buffer = buffer;
+ acomp_ctx->acomp = acomp;
+ acomp_ctx->is_sleepable = acomp_is_async(acomp);
+ acomp_ctx->req = req;
mutex_unlock(&acomp_ctx->mutex);
return 0;
-req_fail:
- crypto_free_acomp(acomp_ctx->acomp);
-acomp_fail:
- kfree(acomp_ctx->buffer);
-buffer_fail:
- mutex_unlock(&acomp_ctx->mutex);
+fail:
+ if (acomp)
+ crypto_free_acomp(acomp);
+ kfree(buffer);
return ret;
}
The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 779b9955f64327c339a16f68055af98252fd3315
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025012001-elbow-configure-d7c7@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 779b9955f64327c339a16f68055af98252fd3315 Mon Sep 17 00:00:00 2001
From: Yosry Ahmed <yosryahmed(a)google.com>
Date: Mon, 13 Jan 2025 21:44:58 +0000
Subject: [PATCH] mm: zswap: move allocations during CPU init outside the lock
In zswap_cpu_comp_prepare(), allocations are made and assigned to various
members of acomp_ctx under acomp_ctx->mutex. However, allocations may
recurse into zswap through reclaim, trying to acquire the same mutex and
deadlocking.
Move the allocations before the mutex critical section. Only the
initialization of acomp_ctx needs to be done with the mutex held.
Link: https://lkml.kernel.org/r/20250113214458.2123410-1-yosryahmed@google.com
Fixes: 12dcb0ef5406 ("mm: zswap: properly synchronize freeing resources during CPU hotunplug")
Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com>
Reviewed-by: Chengming Zhou <chengming.zhou(a)linux.dev>
Cc: Johannes Weiner <hannes(a)cmpxchg.org>
Cc: Nhat Pham <nphamcs(a)gmail.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
diff --git a/mm/zswap.c b/mm/zswap.c
index 30f5a27a6862..b84c20d889b1 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -820,15 +820,15 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
{
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
- struct crypto_acomp *acomp;
- struct acomp_req *req;
+ struct crypto_acomp *acomp = NULL;
+ struct acomp_req *req = NULL;
+ u8 *buffer = NULL;
int ret;
- mutex_lock(&acomp_ctx->mutex);
- acomp_ctx->buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
- if (!acomp_ctx->buffer) {
+ buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
+ if (!buffer) {
ret = -ENOMEM;
- goto buffer_fail;
+ goto fail;
}
acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
@@ -836,21 +836,25 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
pr_err("could not alloc crypto acomp %s : %ld\n",
pool->tfm_name, PTR_ERR(acomp));
ret = PTR_ERR(acomp);
- goto acomp_fail;
+ goto fail;
}
- acomp_ctx->acomp = acomp;
- acomp_ctx->is_sleepable = acomp_is_async(acomp);
- req = acomp_request_alloc(acomp_ctx->acomp);
+ req = acomp_request_alloc(acomp);
if (!req) {
pr_err("could not alloc crypto acomp_request %s\n",
pool->tfm_name);
ret = -ENOMEM;
- goto req_fail;
+ goto fail;
}
- acomp_ctx->req = req;
+ /*
+ * Only hold the mutex after completing allocations, otherwise we may
+ * recurse into zswap through reclaim and attempt to hold the mutex
+ * again resulting in a deadlock.
+ */
+ mutex_lock(&acomp_ctx->mutex);
crypto_init_wait(&acomp_ctx->wait);
+
/*
* if the backend of acomp is async zip, crypto_req_done() will wakeup
* crypto_wait_req(); if the backend of acomp is scomp, the callback
@@ -859,15 +863,17 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_req_done, &acomp_ctx->wait);
+ acomp_ctx->buffer = buffer;
+ acomp_ctx->acomp = acomp;
+ acomp_ctx->is_sleepable = acomp_is_async(acomp);
+ acomp_ctx->req = req;
mutex_unlock(&acomp_ctx->mutex);
return 0;
-req_fail:
- crypto_free_acomp(acomp_ctx->acomp);
-acomp_fail:
- kfree(acomp_ctx->buffer);
-buffer_fail:
- mutex_unlock(&acomp_ctx->mutex);
+fail:
+ if (acomp)
+ crypto_free_acomp(acomp);
+ kfree(buffer);
return ret;
}
The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 779b9955f64327c339a16f68055af98252fd3315
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025012057-carrousel-marbled-221b@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 779b9955f64327c339a16f68055af98252fd3315 Mon Sep 17 00:00:00 2001
From: Yosry Ahmed <yosryahmed(a)google.com>
Date: Mon, 13 Jan 2025 21:44:58 +0000
Subject: [PATCH] mm: zswap: move allocations during CPU init outside the lock
In zswap_cpu_comp_prepare(), allocations are made and assigned to various
members of acomp_ctx under acomp_ctx->mutex. However, allocations may
recurse into zswap through reclaim, trying to acquire the same mutex and
deadlocking.
Move the allocations before the mutex critical section. Only the
initialization of acomp_ctx needs to be done with the mutex held.
Link: https://lkml.kernel.org/r/20250113214458.2123410-1-yosryahmed@google.com
Fixes: 12dcb0ef5406 ("mm: zswap: properly synchronize freeing resources during CPU hotunplug")
Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com>
Reviewed-by: Chengming Zhou <chengming.zhou(a)linux.dev>
Cc: Johannes Weiner <hannes(a)cmpxchg.org>
Cc: Nhat Pham <nphamcs(a)gmail.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
diff --git a/mm/zswap.c b/mm/zswap.c
index 30f5a27a6862..b84c20d889b1 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -820,15 +820,15 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
{
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
- struct crypto_acomp *acomp;
- struct acomp_req *req;
+ struct crypto_acomp *acomp = NULL;
+ struct acomp_req *req = NULL;
+ u8 *buffer = NULL;
int ret;
- mutex_lock(&acomp_ctx->mutex);
- acomp_ctx->buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
- if (!acomp_ctx->buffer) {
+ buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
+ if (!buffer) {
ret = -ENOMEM;
- goto buffer_fail;
+ goto fail;
}
acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
@@ -836,21 +836,25 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
pr_err("could not alloc crypto acomp %s : %ld\n",
pool->tfm_name, PTR_ERR(acomp));
ret = PTR_ERR(acomp);
- goto acomp_fail;
+ goto fail;
}
- acomp_ctx->acomp = acomp;
- acomp_ctx->is_sleepable = acomp_is_async(acomp);
- req = acomp_request_alloc(acomp_ctx->acomp);
+ req = acomp_request_alloc(acomp);
if (!req) {
pr_err("could not alloc crypto acomp_request %s\n",
pool->tfm_name);
ret = -ENOMEM;
- goto req_fail;
+ goto fail;
}
- acomp_ctx->req = req;
+ /*
+ * Only hold the mutex after completing allocations, otherwise we may
+ * recurse into zswap through reclaim and attempt to hold the mutex
+ * again resulting in a deadlock.
+ */
+ mutex_lock(&acomp_ctx->mutex);
crypto_init_wait(&acomp_ctx->wait);
+
/*
* if the backend of acomp is async zip, crypto_req_done() will wakeup
* crypto_wait_req(); if the backend of acomp is scomp, the callback
@@ -859,15 +863,17 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_req_done, &acomp_ctx->wait);
+ acomp_ctx->buffer = buffer;
+ acomp_ctx->acomp = acomp;
+ acomp_ctx->is_sleepable = acomp_is_async(acomp);
+ acomp_ctx->req = req;
mutex_unlock(&acomp_ctx->mutex);
return 0;
-req_fail:
- crypto_free_acomp(acomp_ctx->acomp);
-acomp_fail:
- kfree(acomp_ctx->buffer);
-buffer_fail:
- mutex_unlock(&acomp_ctx->mutex);
+fail:
+ if (acomp)
+ crypto_free_acomp(acomp);
+ kfree(buffer);
return ret;
}
The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 12dcb0ef540629a281533f9dedc1b6b8e14cfb65
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025012015-siren-backyard-e676@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 12dcb0ef540629a281533f9dedc1b6b8e14cfb65 Mon Sep 17 00:00:00 2001
From: Yosry Ahmed <yosryahmed(a)google.com>
Date: Wed, 8 Jan 2025 22:24:41 +0000
Subject: [PATCH] mm: zswap: properly synchronize freeing resources during CPU
hotunplug
In zswap_compress() and zswap_decompress(), the per-CPU acomp_ctx of the
current CPU at the beginning of the operation is retrieved and used
throughout. However, since neither preemption nor migration are disabled,
it is possible that the operation continues on a different CPU.
If the original CPU is hotunplugged while the acomp_ctx is still in use,
we run into a UAF bug as some of the resources attached to the acomp_ctx
are freed during hotunplug in zswap_cpu_comp_dead() (i.e.
acomp_ctx.buffer, acomp_ctx.req, or acomp_ctx.acomp).
The problem was introduced in commit 1ec3b5fe6eec ("mm/zswap: move to use
crypto_acomp API for hardware acceleration") when the switch to the
crypto_acomp API was made. Prior to that, the per-CPU crypto_comp was
retrieved using get_cpu_ptr() which disables preemption and makes sure the
CPU cannot go away from under us. Preemption cannot be disabled with the
crypto_acomp API as a sleepable context is needed.
Use the acomp_ctx.mutex to synchronize CPU hotplug callbacks allocating
and freeing resources with compression/decompression paths. Make sure
that acomp_ctx.req is NULL when the resources are freed. In the
compression/decompression paths, check if acomp_ctx.req is NULL after
acquiring the mutex (meaning the CPU was offlined) and retry on the new
CPU.
The initialization of acomp_ctx.mutex is moved from the CPU hotplug
callback to the pool initialization where it belongs (where the mutex is
allocated). In addition to adding clarity, this makes sure that CPU
hotplug cannot reinitialize a mutex that is already locked by
compression/decompression.
Previously a fix was attempted by holding cpus_read_lock() [1]. This
would have caused a potential deadlock as it is possible for code already
holding the lock to fall into reclaim and enter zswap (causing a
deadlock). A fix was also attempted using SRCU for synchronization, but
Johannes pointed out that synchronize_srcu() cannot be used in CPU hotplug
notifiers [2].
Alternative fixes that were considered/attempted and could have worked:
- Refcounting the per-CPU acomp_ctx. This involves complexity in
handling the race between the refcount dropping to zero in
zswap_[de]compress() and the refcount being re-initialized when the
CPU is onlined.
- Disabling migration before getting the per-CPU acomp_ctx [3], but
that's discouraged and is a much bigger hammer than needed, and could
result in subtle performance issues.
[1]https://lkml.kernel.org/20241219212437.2714151-1-yosryahmed@google.com/
[2]https://lkml.kernel.org/20250107074724.1756696-2-yosryahmed@google.com/
[3]https://lkml.kernel.org/20250107222236.2715883-2-yosryahmed@google.com/
[yosryahmed(a)google.com: remove comment]
Link: https://lkml.kernel.org/r/CAJD7tkaxS1wjn+swugt8QCvQ-rVF5RZnjxwPGX17k8x9zSMa…
Link: https://lkml.kernel.org/r/20250108222441.3622031-1-yosryahmed@google.com
Fixes: 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration")
Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com>
Reported-by: Johannes Weiner <hannes(a)cmpxchg.org>
Closes: https://lore.kernel.org/lkml/20241113213007.GB1564047@cmpxchg.org/
Reported-by: Sam Sun <samsun1006219(a)gmail.com>
Closes: https://lore.kernel.org/lkml/CAEkJfYMtSdM5HceNsXUDf5haghD5+o2e7Qv4OcuruL4tP…
Cc: Barry Song <baohua(a)kernel.org>
Cc: Chengming Zhou <chengming.zhou(a)linux.dev>
Cc: Kanchana P Sridhar <kanchana.p.sridhar(a)intel.com>
Cc: Nhat Pham <nphamcs(a)gmail.com>
Cc: Vitaly Wool <vitalywool(a)gmail.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
diff --git a/mm/zswap.c b/mm/zswap.c
index f6316b66fb23..30f5a27a6862 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -251,7 +251,7 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
struct zswap_pool *pool;
char name[38]; /* 'zswap' + 32 char (max) num + \0 */
gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
- int ret;
+ int ret, cpu;
if (!zswap_has_pool) {
/* if either are unset, pool initialization failed, and we
@@ -285,6 +285,9 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
goto error;
}
+ for_each_possible_cpu(cpu)
+ mutex_init(&per_cpu_ptr(pool->acomp_ctx, cpu)->mutex);
+
ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE,
&pool->node);
if (ret)
@@ -821,11 +824,12 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
struct acomp_req *req;
int ret;
- mutex_init(&acomp_ctx->mutex);
-
+ mutex_lock(&acomp_ctx->mutex);
acomp_ctx->buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
- if (!acomp_ctx->buffer)
- return -ENOMEM;
+ if (!acomp_ctx->buffer) {
+ ret = -ENOMEM;
+ goto buffer_fail;
+ }
acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
if (IS_ERR(acomp)) {
@@ -855,12 +859,15 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_req_done, &acomp_ctx->wait);
+ mutex_unlock(&acomp_ctx->mutex);
return 0;
req_fail:
crypto_free_acomp(acomp_ctx->acomp);
acomp_fail:
kfree(acomp_ctx->buffer);
+buffer_fail:
+ mutex_unlock(&acomp_ctx->mutex);
return ret;
}
@@ -869,17 +876,45 @@ static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
+ mutex_lock(&acomp_ctx->mutex);
if (!IS_ERR_OR_NULL(acomp_ctx)) {
if (!IS_ERR_OR_NULL(acomp_ctx->req))
acomp_request_free(acomp_ctx->req);
+ acomp_ctx->req = NULL;
if (!IS_ERR_OR_NULL(acomp_ctx->acomp))
crypto_free_acomp(acomp_ctx->acomp);
kfree(acomp_ctx->buffer);
}
+ mutex_unlock(&acomp_ctx->mutex);
return 0;
}
+static struct crypto_acomp_ctx *acomp_ctx_get_cpu_lock(struct zswap_pool *pool)
+{
+ struct crypto_acomp_ctx *acomp_ctx;
+
+ for (;;) {
+ acomp_ctx = raw_cpu_ptr(pool->acomp_ctx);
+ mutex_lock(&acomp_ctx->mutex);
+ if (likely(acomp_ctx->req))
+ return acomp_ctx;
+ /*
+ * It is possible that we were migrated to a different CPU after
+ * getting the per-CPU ctx but before the mutex was acquired. If
+ * the old CPU got offlined, zswap_cpu_comp_dead() could have
+ * already freed ctx->req (among other things) and set it to
+ * NULL. Just try again on the new CPU that we ended up on.
+ */
+ mutex_unlock(&acomp_ctx->mutex);
+ }
+}
+
+static void acomp_ctx_put_unlock(struct crypto_acomp_ctx *acomp_ctx)
+{
+ mutex_unlock(&acomp_ctx->mutex);
+}
+
static bool zswap_compress(struct page *page, struct zswap_entry *entry,
struct zswap_pool *pool)
{
@@ -893,10 +928,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry,
gfp_t gfp;
u8 *dst;
- acomp_ctx = raw_cpu_ptr(pool->acomp_ctx);
-
- mutex_lock(&acomp_ctx->mutex);
-
+ acomp_ctx = acomp_ctx_get_cpu_lock(pool);
dst = acomp_ctx->buffer;
sg_init_table(&input, 1);
sg_set_page(&input, page, PAGE_SIZE, 0);
@@ -949,7 +981,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry,
else if (alloc_ret)
zswap_reject_alloc_fail++;
- mutex_unlock(&acomp_ctx->mutex);
+ acomp_ctx_put_unlock(acomp_ctx);
return comp_ret == 0 && alloc_ret == 0;
}
@@ -960,9 +992,7 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio)
struct crypto_acomp_ctx *acomp_ctx;
u8 *src;
- acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
- mutex_lock(&acomp_ctx->mutex);
-
+ acomp_ctx = acomp_ctx_get_cpu_lock(entry->pool);
src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO);
/*
* If zpool_map_handle is atomic, we cannot reliably utilize its mapped buffer
@@ -986,10 +1016,10 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio)
acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, PAGE_SIZE);
BUG_ON(crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait));
BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE);
- mutex_unlock(&acomp_ctx->mutex);
if (src != acomp_ctx->buffer)
zpool_unmap_handle(zpool, entry->handle);
+ acomp_ctx_put_unlock(acomp_ctx);
}
/*********************************
The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 12dcb0ef540629a281533f9dedc1b6b8e14cfb65
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025012014-sardine-hardwood-6828@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 12dcb0ef540629a281533f9dedc1b6b8e14cfb65 Mon Sep 17 00:00:00 2001
From: Yosry Ahmed <yosryahmed(a)google.com>
Date: Wed, 8 Jan 2025 22:24:41 +0000
Subject: [PATCH] mm: zswap: properly synchronize freeing resources during CPU
hotunplug
In zswap_compress() and zswap_decompress(), the per-CPU acomp_ctx of the
current CPU at the beginning of the operation is retrieved and used
throughout. However, since neither preemption nor migration are disabled,
it is possible that the operation continues on a different CPU.
If the original CPU is hotunplugged while the acomp_ctx is still in use,
we run into a UAF bug as some of the resources attached to the acomp_ctx
are freed during hotunplug in zswap_cpu_comp_dead() (i.e.
acomp_ctx.buffer, acomp_ctx.req, or acomp_ctx.acomp).
The problem was introduced in commit 1ec3b5fe6eec ("mm/zswap: move to use
crypto_acomp API for hardware acceleration") when the switch to the
crypto_acomp API was made. Prior to that, the per-CPU crypto_comp was
retrieved using get_cpu_ptr() which disables preemption and makes sure the
CPU cannot go away from under us. Preemption cannot be disabled with the
crypto_acomp API as a sleepable context is needed.
Use the acomp_ctx.mutex to synchronize CPU hotplug callbacks allocating
and freeing resources with compression/decompression paths. Make sure
that acomp_ctx.req is NULL when the resources are freed. In the
compression/decompression paths, check if acomp_ctx.req is NULL after
acquiring the mutex (meaning the CPU was offlined) and retry on the new
CPU.
The initialization of acomp_ctx.mutex is moved from the CPU hotplug
callback to the pool initialization where it belongs (where the mutex is
allocated). In addition to adding clarity, this makes sure that CPU
hotplug cannot reinitialize a mutex that is already locked by
compression/decompression.
Previously a fix was attempted by holding cpus_read_lock() [1]. This
would have caused a potential deadlock as it is possible for code already
holding the lock to fall into reclaim and enter zswap (causing a
deadlock). A fix was also attempted using SRCU for synchronization, but
Johannes pointed out that synchronize_srcu() cannot be used in CPU hotplug
notifiers [2].
Alternative fixes that were considered/attempted and could have worked:
- Refcounting the per-CPU acomp_ctx. This involves complexity in
handling the race between the refcount dropping to zero in
zswap_[de]compress() and the refcount being re-initialized when the
CPU is onlined.
- Disabling migration before getting the per-CPU acomp_ctx [3], but
that's discouraged and is a much bigger hammer than needed, and could
result in subtle performance issues.
[1]https://lkml.kernel.org/20241219212437.2714151-1-yosryahmed@google.com/
[2]https://lkml.kernel.org/20250107074724.1756696-2-yosryahmed@google.com/
[3]https://lkml.kernel.org/20250107222236.2715883-2-yosryahmed@google.com/
[yosryahmed(a)google.com: remove comment]
Link: https://lkml.kernel.org/r/CAJD7tkaxS1wjn+swugt8QCvQ-rVF5RZnjxwPGX17k8x9zSMa…
Link: https://lkml.kernel.org/r/20250108222441.3622031-1-yosryahmed@google.com
Fixes: 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration")
Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com>
Reported-by: Johannes Weiner <hannes(a)cmpxchg.org>
Closes: https://lore.kernel.org/lkml/20241113213007.GB1564047@cmpxchg.org/
Reported-by: Sam Sun <samsun1006219(a)gmail.com>
Closes: https://lore.kernel.org/lkml/CAEkJfYMtSdM5HceNsXUDf5haghD5+o2e7Qv4OcuruL4tP…
Cc: Barry Song <baohua(a)kernel.org>
Cc: Chengming Zhou <chengming.zhou(a)linux.dev>
Cc: Kanchana P Sridhar <kanchana.p.sridhar(a)intel.com>
Cc: Nhat Pham <nphamcs(a)gmail.com>
Cc: Vitaly Wool <vitalywool(a)gmail.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
diff --git a/mm/zswap.c b/mm/zswap.c
index f6316b66fb23..30f5a27a6862 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -251,7 +251,7 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
struct zswap_pool *pool;
char name[38]; /* 'zswap' + 32 char (max) num + \0 */
gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
- int ret;
+ int ret, cpu;
if (!zswap_has_pool) {
/* if either are unset, pool initialization failed, and we
@@ -285,6 +285,9 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
goto error;
}
+ for_each_possible_cpu(cpu)
+ mutex_init(&per_cpu_ptr(pool->acomp_ctx, cpu)->mutex);
+
ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE,
&pool->node);
if (ret)
@@ -821,11 +824,12 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
struct acomp_req *req;
int ret;
- mutex_init(&acomp_ctx->mutex);
-
+ mutex_lock(&acomp_ctx->mutex);
acomp_ctx->buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
- if (!acomp_ctx->buffer)
- return -ENOMEM;
+ if (!acomp_ctx->buffer) {
+ ret = -ENOMEM;
+ goto buffer_fail;
+ }
acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
if (IS_ERR(acomp)) {
@@ -855,12 +859,15 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_req_done, &acomp_ctx->wait);
+ mutex_unlock(&acomp_ctx->mutex);
return 0;
req_fail:
crypto_free_acomp(acomp_ctx->acomp);
acomp_fail:
kfree(acomp_ctx->buffer);
+buffer_fail:
+ mutex_unlock(&acomp_ctx->mutex);
return ret;
}
@@ -869,17 +876,45 @@ static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
+ mutex_lock(&acomp_ctx->mutex);
if (!IS_ERR_OR_NULL(acomp_ctx)) {
if (!IS_ERR_OR_NULL(acomp_ctx->req))
acomp_request_free(acomp_ctx->req);
+ acomp_ctx->req = NULL;
if (!IS_ERR_OR_NULL(acomp_ctx->acomp))
crypto_free_acomp(acomp_ctx->acomp);
kfree(acomp_ctx->buffer);
}
+ mutex_unlock(&acomp_ctx->mutex);
return 0;
}
+static struct crypto_acomp_ctx *acomp_ctx_get_cpu_lock(struct zswap_pool *pool)
+{
+ struct crypto_acomp_ctx *acomp_ctx;
+
+ for (;;) {
+ acomp_ctx = raw_cpu_ptr(pool->acomp_ctx);
+ mutex_lock(&acomp_ctx->mutex);
+ if (likely(acomp_ctx->req))
+ return acomp_ctx;
+ /*
+ * It is possible that we were migrated to a different CPU after
+ * getting the per-CPU ctx but before the mutex was acquired. If
+ * the old CPU got offlined, zswap_cpu_comp_dead() could have
+ * already freed ctx->req (among other things) and set it to
+ * NULL. Just try again on the new CPU that we ended up on.
+ */
+ mutex_unlock(&acomp_ctx->mutex);
+ }
+}
+
+static void acomp_ctx_put_unlock(struct crypto_acomp_ctx *acomp_ctx)
+{
+ mutex_unlock(&acomp_ctx->mutex);
+}
+
static bool zswap_compress(struct page *page, struct zswap_entry *entry,
struct zswap_pool *pool)
{
@@ -893,10 +928,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry,
gfp_t gfp;
u8 *dst;
- acomp_ctx = raw_cpu_ptr(pool->acomp_ctx);
-
- mutex_lock(&acomp_ctx->mutex);
-
+ acomp_ctx = acomp_ctx_get_cpu_lock(pool);
dst = acomp_ctx->buffer;
sg_init_table(&input, 1);
sg_set_page(&input, page, PAGE_SIZE, 0);
@@ -949,7 +981,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry,
else if (alloc_ret)
zswap_reject_alloc_fail++;
- mutex_unlock(&acomp_ctx->mutex);
+ acomp_ctx_put_unlock(acomp_ctx);
return comp_ret == 0 && alloc_ret == 0;
}
@@ -960,9 +992,7 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio)
struct crypto_acomp_ctx *acomp_ctx;
u8 *src;
- acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
- mutex_lock(&acomp_ctx->mutex);
-
+ acomp_ctx = acomp_ctx_get_cpu_lock(entry->pool);
src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO);
/*
* If zpool_map_handle is atomic, we cannot reliably utilize its mapped buffer
@@ -986,10 +1016,10 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio)
acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, PAGE_SIZE);
BUG_ON(crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait));
BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE);
- mutex_unlock(&acomp_ctx->mutex);
if (src != acomp_ctx->buffer)
zpool_unmap_handle(zpool, entry->handle);
+ acomp_ctx_put_unlock(acomp_ctx);
}
/*********************************
From: lei lu <llfamsec(a)gmail.com>
commit fb63435b7c7dc112b1ae1baea5486e0a6e27b196 upstream.
There is a lack of verification of the space occupied by fixed members
of xlog_op_header in the xlog_recover_process_data.
We can create a crafted image to trigger an out of bounds read by
following these steps:
1) Mount an image of xfs, and do some file operations to leave records
2) Before umounting, copy the image for subsequent steps to simulate
abnormal exit. Because umount will ensure that tail_blk and
head_blk are the same, which will result in the inability to enter
xlog_recover_process_data
3) Write a tool to parse and modify the copied image in step 2
4) Make the end of the xlog_op_header entries only 1 byte away from
xlog_rec_header->h_size
5) xlog_rec_header->h_num_logops++
6) Modify xlog_rec_header->h_crc
Fix:
Add a check to make sure there is sufficient space to access fixed members
of xlog_op_header.
Signed-off-by: lei lu <llfamsec(a)gmail.com>
Reviewed-by: Dave Chinner <dchinner(a)redhat.com>
Reviewed-by: Darrick J. Wong <djwong(a)kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu(a)kernel.org>
Signed-off-by: Denis Arefev <arefev(a)swemel.ru>
---
Backport fix for CVE-2024-41014
Link: https://nvd.nist.gov/vuln/detail/cve-2024-41014
---
fs/xfs/xfs_log_recover.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index e61f28ce3e44..eafe76f304ef 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -2419,7 +2419,10 @@ xlog_recover_process_data(
ohead = (struct xlog_op_header *)dp;
dp += sizeof(*ohead);
- ASSERT(dp <= end);
+ if (dp > end) {
+ xfs_warn(log->l_mp, "%s: op header overrun", __func__);
+ return -EFSCORRUPTED;
+ }
/* errors will abort recovery */
error = xlog_recover_process_ophdr(log, rhash, rhead, ohead,
--
2.43.0