This is a note to let you know that I've just added the patch titled
ptr_ring: try vmalloc() when kmalloc() fails
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
ptr_ring-try-vmalloc-when-kmalloc-fails.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From 0bf7800f1799b5b1fd7d4f024e9ece53ac489011 Mon Sep 17 00:00:00 2001
From: Jason Wang <jasowang(a)redhat.com>
Date: Fri, 9 Feb 2018 17:45:50 +0800
Subject: ptr_ring: try vmalloc() when kmalloc() fails
From: Jason Wang <jasowang(a)redhat.com>
commit 0bf7800f1799b5b1fd7d4f024e9ece53ac489011 upstream.
This patch switch to use kvmalloc_array() for using a vmalloc()
fallback to help in case kmalloc() fails.
Reported-by: syzbot+e4d4f9ddd4295539735d(a)syzkaller.appspotmail.com
Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
Signed-off-by: Jason Wang <jasowang(a)redhat.com>
Acked-by: Michael S. Tsirkin <mst(a)redhat.com>
Signed-off-by: David S. Miller <davem(a)davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
include/linux/ptr_ring.h | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -451,11 +451,14 @@ static inline int ptr_ring_consume_batch
__PTR_RING_PEEK_CALL_v; \
})
+/* Not all gfp_t flags (besides GFP_KERNEL) are allowed. See
+ * documentation for vmalloc for which of them are legal.
+ */
static inline void **__ptr_ring_init_queue_alloc(unsigned int size, gfp_t gfp)
{
if (size * sizeof(void *) > KMALLOC_MAX_SIZE)
return NULL;
- return kcalloc(size, sizeof(void *), gfp);
+ return kvmalloc_array(size, sizeof(void *), gfp | __GFP_ZERO);
}
static inline void __ptr_ring_set_size(struct ptr_ring *r, int size)
@@ -588,7 +591,7 @@ static inline int ptr_ring_resize(struct
spin_unlock(&(r)->producer_lock);
spin_unlock_irqrestore(&(r)->consumer_lock, flags);
- kfree(old);
+ kvfree(old);
return 0;
}
@@ -628,7 +631,7 @@ static inline int ptr_ring_resize_multip
}
for (i = 0; i < nrings; ++i)
- kfree(queues[i]);
+ kvfree(queues[i]);
kfree(queues);
@@ -636,7 +639,7 @@ static inline int ptr_ring_resize_multip
nomem:
while (--i >= 0)
- kfree(queues[i]);
+ kvfree(queues[i]);
kfree(queues);
@@ -651,7 +654,7 @@ static inline void ptr_ring_cleanup(stru
if (destroy)
while ((ptr = ptr_ring_consume(r)))
destroy(ptr);
- kfree(r->queue);
+ kvfree(r->queue);
}
#endif /* _LINUX_PTR_RING_H */
Patches currently in stable-queue which might be from jasowang(a)redhat.com are
queue-4.15/ptr_ring-try-vmalloc-when-kmalloc-fails.patch
queue-4.15/ptr_ring-fail-early-if-queue-occupies-more-than-kmalloc_max_size.patch
This is a note to let you know that I've just added the patch titled
netfilter: xt_RATEEST: acquire xt_rateest_mutex for hash insert
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
netfilter-xt_rateest-acquire-xt_rateest_mutex-for-hash-insert.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From 7dc68e98757a8eccf8ca7a53a29b896f1eef1f76 Mon Sep 17 00:00:00 2001
From: Cong Wang <xiyou.wangcong(a)gmail.com>
Date: Mon, 5 Feb 2018 14:41:45 -0800
Subject: netfilter: xt_RATEEST: acquire xt_rateest_mutex for hash insert
From: Cong Wang <xiyou.wangcong(a)gmail.com>
commit 7dc68e98757a8eccf8ca7a53a29b896f1eef1f76 upstream.
rateest_hash is supposed to be protected by xt_rateest_mutex,
and, as suggested by Eric, lookup and insert should be atomic,
so we should acquire the xt_rateest_mutex once for both.
So introduce a non-locking helper for internal use and keep the
locking one for external.
Reported-by: <syzbot+5cb189720978275e4c75(a)syzkaller.appspotmail.com>
Fixes: 5859034d7eb8 ("[NETFILTER]: x_tables: add RATEEST target")
Signed-off-by: Cong Wang <xiyou.wangcong(a)gmail.com>
Reviewed-by: Florian Westphal <fw(a)strlen.de>
Reviewed-by: Eric Dumazet <edumazet(a)google.com>
Signed-off-by: Pablo Neira Ayuso <pablo(a)netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
net/netfilter/xt_RATEEST.c | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)
--- a/net/netfilter/xt_RATEEST.c
+++ b/net/netfilter/xt_RATEEST.c
@@ -39,23 +39,31 @@ static void xt_rateest_hash_insert(struc
hlist_add_head(&est->list, &rateest_hash[h]);
}
-struct xt_rateest *xt_rateest_lookup(const char *name)
+static struct xt_rateest *__xt_rateest_lookup(const char *name)
{
struct xt_rateest *est;
unsigned int h;
h = xt_rateest_hash(name);
- mutex_lock(&xt_rateest_mutex);
hlist_for_each_entry(est, &rateest_hash[h], list) {
if (strcmp(est->name, name) == 0) {
est->refcnt++;
- mutex_unlock(&xt_rateest_mutex);
return est;
}
}
- mutex_unlock(&xt_rateest_mutex);
+
return NULL;
}
+
+struct xt_rateest *xt_rateest_lookup(const char *name)
+{
+ struct xt_rateest *est;
+
+ mutex_lock(&xt_rateest_mutex);
+ est = __xt_rateest_lookup(name);
+ mutex_unlock(&xt_rateest_mutex);
+ return est;
+}
EXPORT_SYMBOL_GPL(xt_rateest_lookup);
void xt_rateest_put(struct xt_rateest *est)
@@ -100,8 +108,10 @@ static int xt_rateest_tg_checkentry(cons
net_get_random_once(&jhash_rnd, sizeof(jhash_rnd));
- est = xt_rateest_lookup(info->name);
+ mutex_lock(&xt_rateest_mutex);
+ est = __xt_rateest_lookup(info->name);
if (est) {
+ mutex_unlock(&xt_rateest_mutex);
/*
* If estimator parameters are specified, they must match the
* existing estimator.
@@ -139,11 +149,13 @@ static int xt_rateest_tg_checkentry(cons
info->est = est;
xt_rateest_hash_insert(est);
+ mutex_unlock(&xt_rateest_mutex);
return 0;
err2:
kfree(est);
err1:
+ mutex_unlock(&xt_rateest_mutex);
return ret;
}
Patches currently in stable-queue which might be from xiyou.wangcong(a)gmail.com are
queue-4.15/net_sched-gen_estimator-fix-lockdep-splat.patch
queue-4.15/netfilter-xt_cgroup-initialize-info-priv-in-cgroup_mt_check_v1.patch
queue-4.15/netfilter-xt_rateest-acquire-xt_rateest_mutex-for-hash-insert.patch
This is a note to let you know that I've just added the patch titled
netfilter: x_tables: fix int overflow in xt_alloc_table_info()
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
netfilter-x_tables-fix-int-overflow-in-xt_alloc_table_info.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From 889c604fd0b5f6d3b8694ade229ee44124de1127 Mon Sep 17 00:00:00 2001
From: Dmitry Vyukov <dvyukov(a)google.com>
Date: Thu, 28 Dec 2017 09:48:54 +0100
Subject: netfilter: x_tables: fix int overflow in xt_alloc_table_info()
From: Dmitry Vyukov <dvyukov(a)google.com>
commit 889c604fd0b5f6d3b8694ade229ee44124de1127 upstream.
syzkaller triggered OOM kills by passing ipt_replace.size = -1
to IPT_SO_SET_REPLACE. The root cause is that SMP_ALIGN() in
xt_alloc_table_info() causes int overflow and the size check passes
when it should not. SMP_ALIGN() is no longer needed leftover.
Remove SMP_ALIGN() call in xt_alloc_table_info().
Reported-by: syzbot+4396883fa8c4f64e0175(a)syzkaller.appspotmail.com
Signed-off-by: Dmitry Vyukov <dvyukov(a)google.com>
Signed-off-by: Pablo Neira Ayuso <pablo(a)netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
net/netfilter/x_tables.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -39,7 +39,6 @@ MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge(a)netfilter.org>");
MODULE_DESCRIPTION("{ip,ip6,arp,eb}_tables backend module");
-#define SMP_ALIGN(x) (((x) + SMP_CACHE_BYTES-1) & ~(SMP_CACHE_BYTES-1))
#define XT_PCPU_BLOCK_SIZE 4096
struct compat_delta {
@@ -1000,7 +999,7 @@ struct xt_table_info *xt_alloc_table_inf
return NULL;
/* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
- if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > totalram_pages)
+ if ((size >> PAGE_SHIFT) + 2 > totalram_pages)
return NULL;
info = kvmalloc(sz, GFP_KERNEL);
Patches currently in stable-queue which might be from dvyukov(a)google.com are
queue-4.15/kvm-x86-fix-escape-of-guest-dr6-to-the-host.patch
queue-4.15/netfilter-x_tables-fix-int-overflow-in-xt_alloc_table_info.patch
queue-4.15/netfilter-ipt_clusterip-fix-out-of-bounds-accesses-in-clusterip_tg_check.patch
queue-4.15/kcov-detect-double-association-with-a-single-task.patch
This is a note to let you know that I've just added the patch titled
netfilter: xt_cgroup: initialize info->priv in cgroup_mt_check_v1()
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
netfilter-xt_cgroup-initialize-info-priv-in-cgroup_mt_check_v1.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From ba7cd5d95f25cc6005f687dabdb4e7a6063adda9 Mon Sep 17 00:00:00 2001
From: Cong Wang <xiyou.wangcong(a)gmail.com>
Date: Wed, 31 Jan 2018 15:02:47 -0800
Subject: netfilter: xt_cgroup: initialize info->priv in cgroup_mt_check_v1()
From: Cong Wang <xiyou.wangcong(a)gmail.com>
commit ba7cd5d95f25cc6005f687dabdb4e7a6063adda9 upstream.
xt_cgroup_info_v1->priv is an internal pointer only used for kernel,
we should not trust what user-space provides.
Reported-by: <syzbot+4fbcfcc0d2e6592bd641(a)syzkaller.appspotmail.com>
Fixes: c38c4597e4bf ("netfilter: implement xt_cgroup cgroup2 path match")
Cc: Pablo Neira Ayuso <pablo(a)netfilter.org>
Signed-off-by: Cong Wang <xiyou.wangcong(a)gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo(a)netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
net/netfilter/xt_cgroup.c | 1 +
1 file changed, 1 insertion(+)
--- a/net/netfilter/xt_cgroup.c
+++ b/net/netfilter/xt_cgroup.c
@@ -52,6 +52,7 @@ static int cgroup_mt_check_v1(const stru
return -EINVAL;
}
+ info->priv = NULL;
if (info->has_path) {
cgrp = cgroup_get_from_path(info->path);
if (IS_ERR(cgrp)) {
Patches currently in stable-queue which might be from xiyou.wangcong(a)gmail.com are
queue-4.15/net_sched-gen_estimator-fix-lockdep-splat.patch
queue-4.15/netfilter-xt_cgroup-initialize-info-priv-in-cgroup_mt_check_v1.patch
queue-4.15/netfilter-xt_rateest-acquire-xt_rateest_mutex-for-hash-insert.patch
This is a note to let you know that I've just added the patch titled
netfilter: x_tables: avoid out-of-bounds reads in xt_request_find_{match|target}
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
netfilter-x_tables-avoid-out-of-bounds-reads-in-xt_request_find_-match-target.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From da17c73b6eb74aad3c3c0654394635675b623b3e Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet(a)google.com>
Date: Wed, 24 Jan 2018 17:16:09 -0800
Subject: netfilter: x_tables: avoid out-of-bounds reads in xt_request_find_{match|target}
From: Eric Dumazet <edumazet(a)google.com>
commit da17c73b6eb74aad3c3c0654394635675b623b3e upstream.
It looks like syzbot found its way into netfilter territory.
Issue here is that @name comes from user space and might
not be null terminated.
Out-of-bound reads happen, KASAN is not happy.
v2 added similar fix for xt_request_find_target(),
as Florian advised.
Signed-off-by: Eric Dumazet <edumazet(a)google.com>
Reported-by: syzbot <syzkaller(a)googlegroups.com>
Acked-by: Florian Westphal <fw(a)strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo(a)netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
net/netfilter/x_tables.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -209,6 +209,9 @@ xt_request_find_match(uint8_t nfproto, c
{
struct xt_match *match;
+ if (strnlen(name, XT_EXTENSION_MAXNAMELEN) == XT_EXTENSION_MAXNAMELEN)
+ return ERR_PTR(-EINVAL);
+
match = xt_find_match(nfproto, name, revision);
if (IS_ERR(match)) {
request_module("%st_%s", xt_prefix[nfproto], name);
@@ -251,6 +254,9 @@ struct xt_target *xt_request_find_target
{
struct xt_target *target;
+ if (strnlen(name, XT_EXTENSION_MAXNAMELEN) == XT_EXTENSION_MAXNAMELEN)
+ return ERR_PTR(-EINVAL);
+
target = xt_find_target(af, name, revision);
if (IS_ERR(target)) {
request_module("%st_%s", xt_prefix[af], name);
Patches currently in stable-queue which might be from edumazet(a)google.com are
queue-4.15/net_sched-gen_estimator-fix-lockdep-splat.patch
queue-4.15/tun-fix-tun_napi_alloc_frags-frag-allocator.patch
queue-4.15/netfilter-x_tables-avoid-out-of-bounds-reads-in-xt_request_find_-match-target.patch
queue-4.15/netfilter-xt_rateest-acquire-xt_rateest_mutex-for-hash-insert.patch
This is a note to let you know that I've just added the patch titled
net_sched: gen_estimator: fix lockdep splat
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
net_sched-gen_estimator-fix-lockdep-splat.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From 40ca54e3a686f13117f3de0c443f8026dadf7c44 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet(a)google.com>
Date: Sat, 27 Jan 2018 10:58:43 -0800
Subject: net_sched: gen_estimator: fix lockdep splat
From: Eric Dumazet <edumazet(a)google.com>
commit 40ca54e3a686f13117f3de0c443f8026dadf7c44 upstream.
syzbot reported a lockdep splat in gen_new_estimator() /
est_fetch_counters() when attempting to lock est->stats_lock.
Since est_fetch_counters() is called from BH context from timer
interrupt, we need to block BH as well when calling it from process
context.
Most qdiscs use per cpu counters and are immune to the problem,
but net/sched/act_api.c and net/netfilter/xt_RATEEST.c are using
a spinlock to protect their data. They both call gen_new_estimator()
while object is created and not yet alive, so this bug could
not trigger a deadlock, only a lockdep splat.
Fixes: 1c0d32fde5bd ("net_sched: gen_estimator: complete rewrite of rate estimators")
Signed-off-by: Eric Dumazet <edumazet(a)google.com>
Reported-by: syzbot <syzkaller(a)googlegroups.com>
Acked-by: Cong Wang <xiyou.wangcong(a)gmail.com>
Signed-off-by: David S. Miller <davem(a)davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
net/core/gen_estimator.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/net/core/gen_estimator.c
+++ b/net/core/gen_estimator.c
@@ -159,7 +159,11 @@ int gen_new_estimator(struct gnet_stats_
est->intvl_log = intvl_log;
est->cpu_bstats = cpu_bstats;
+ if (stats_lock)
+ local_bh_disable();
est_fetch_counters(est, &b);
+ if (stats_lock)
+ local_bh_enable();
est->last_bytes = b.bytes;
est->last_packets = b.packets;
old = rcu_dereference_protected(*rate_est, 1);
Patches currently in stable-queue which might be from edumazet(a)google.com are
queue-4.15/net_sched-gen_estimator-fix-lockdep-splat.patch
queue-4.15/tun-fix-tun_napi_alloc_frags-frag-allocator.patch
queue-4.15/netfilter-x_tables-avoid-out-of-bounds-reads-in-xt_request_find_-match-target.patch
queue-4.15/netfilter-xt_rateest-acquire-xt_rateest_mutex-for-hash-insert.patch
This is a note to let you know that I've just added the patch titled
netfilter: ipt_CLUSTERIP: fix out-of-bounds accesses in clusterip_tg_check()
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
netfilter-ipt_clusterip-fix-out-of-bounds-accesses-in-clusterip_tg_check.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From 1a38956cce5eabd7b74f94bab70265e4df83165e Mon Sep 17 00:00:00 2001
From: Dmitry Vyukov <dvyukov(a)google.com>
Date: Tue, 30 Jan 2018 15:21:34 +0100
Subject: netfilter: ipt_CLUSTERIP: fix out-of-bounds accesses in clusterip_tg_check()
From: Dmitry Vyukov <dvyukov(a)google.com>
commit 1a38956cce5eabd7b74f94bab70265e4df83165e upstream.
Commit 136e92bbec0a switched local_nodes from an array to a bitmask
but did not add proper bounds checks. As the result
clusterip_config_init_nodelist() can both over-read
ipt_clusterip_tgt_info.local_nodes and over-write
clusterip_config.local_nodes.
Add bounds checks for both.
Fixes: 136e92bbec0a ("[NETFILTER] CLUSTERIP: use a bitmap to store node responsibility data")
Signed-off-by: Dmitry Vyukov <dvyukov(a)google.com>
Reported-by: syzbot <syzkaller(a)googlegroups.com>
Signed-off-by: Pablo Neira Ayuso <pablo(a)netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
net/ipv4/netfilter/ipt_CLUSTERIP.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -431,7 +431,7 @@ static int clusterip_tg_check(const stru
struct ipt_clusterip_tgt_info *cipinfo = par->targinfo;
const struct ipt_entry *e = par->entryinfo;
struct clusterip_config *config;
- int ret;
+ int ret, i;
if (par->nft_compat) {
pr_err("cannot use CLUSTERIP target from nftables compat\n");
@@ -450,8 +450,18 @@ static int clusterip_tg_check(const stru
pr_info("Please specify destination IP\n");
return -EINVAL;
}
-
- /* FIXME: further sanity checks */
+ if (cipinfo->num_local_nodes > ARRAY_SIZE(cipinfo->local_nodes)) {
+ pr_info("bad num_local_nodes %u\n", cipinfo->num_local_nodes);
+ return -EINVAL;
+ }
+ for (i = 0; i < cipinfo->num_local_nodes; i++) {
+ if (cipinfo->local_nodes[i] - 1 >=
+ sizeof(config->local_nodes) * 8) {
+ pr_info("bad local_nodes[%d] %u\n",
+ i, cipinfo->local_nodes[i]);
+ return -EINVAL;
+ }
+ }
config = clusterip_config_find_get(par->net, e->ip.dst.s_addr, 1);
if (!config) {
Patches currently in stable-queue which might be from dvyukov(a)google.com are
queue-4.15/kvm-x86-fix-escape-of-guest-dr6-to-the-host.patch
queue-4.15/netfilter-x_tables-fix-int-overflow-in-xt_alloc_table_info.patch
queue-4.15/netfilter-ipt_clusterip-fix-out-of-bounds-accesses-in-clusterip_tg_check.patch
queue-4.15/kcov-detect-double-association-with-a-single-task.patch
This is a note to let you know that I've just added the patch titled
KVM: x86: fix escape of guest dr6 to the host
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
kvm-x86-fix-escape-of-guest-dr6-to-the-host.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From efdab992813fb2ed825745625b83c05032e9cda2 Mon Sep 17 00:00:00 2001
From: Wanpeng Li <wanpeng.li(a)hotmail.com>
Date: Wed, 13 Dec 2017 10:46:40 +0100
Subject: KVM: x86: fix escape of guest dr6 to the host
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
From: Wanpeng Li <wanpeng.li(a)hotmail.com>
commit efdab992813fb2ed825745625b83c05032e9cda2 upstream.
syzkaller reported:
WARNING: CPU: 0 PID: 12927 at arch/x86/kernel/traps.c:780 do_debug+0x222/0x250
CPU: 0 PID: 12927 Comm: syz-executor Tainted: G OE 4.15.0-rc2+ #16
RIP: 0010:do_debug+0x222/0x250
Call Trace:
<#DB>
debug+0x3e/0x70
RIP: 0010:copy_user_enhanced_fast_string+0x10/0x20
</#DB>
_copy_from_user+0x5b/0x90
SyS_timer_create+0x33/0x80
entry_SYSCALL_64_fastpath+0x23/0x9a
The testcase sets a watchpoint (with perf_event_open) on a buffer that is
passed to timer_create() as the struct sigevent argument. In timer_create(),
copy_from_user()'s rep movsb triggers the BP. The testcase also sets
the debug registers for the guest.
However, KVM only restores host debug registers when the host has active
watchpoints, which triggers a race condition when running the testcase with
multiple threads. The guest's DR6.BS bit can escape to the host before
another thread invokes timer_create(), and do_debug() complains.
The fix is to respect do_debug()'s dr6 invariant when leaving KVM.
Reported-by: Dmitry Vyukov <dvyukov(a)google.com>
Cc: Paolo Bonzini <pbonzini(a)redhat.com>
Cc: Radim Krčmář <rkrcmar(a)redhat.com>
Cc: David Hildenbrand <david(a)redhat.com>
Cc: Dmitry Vyukov <dvyukov(a)google.com>
Reviewed-by: David Hildenbrand <david(a)redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li(a)hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar(a)redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
arch/x86/kvm/x86.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2939,6 +2939,12 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *
pagefault_enable();
kvm_x86_ops->vcpu_put(vcpu);
vcpu->arch.last_host_tsc = rdtsc();
+ /*
+ * If userspace has set any breakpoints or watchpoints, dr6 is restored
+ * on every vmexit, but if not, we might have a stale dr6 from the
+ * guest. do_debug expects dr6 to be cleared after it runs, do the same.
+ */
+ set_debugreg(0, 6);
}
static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu,
Patches currently in stable-queue which might be from wanpeng.li(a)hotmail.com are
queue-4.15/kvm-x86-fix-escape-of-guest-dr6-to-the-host.patch