object_err() reports details of an object for further debugging, such as
the freelist pointer, redzone, etc. However, if the pointer is invalid,
attempting to access object metadata can lead to a crash since it does
not point to a valid object.
In case the pointer is NULL or check_valid_pointer() returns false for
the pointer, only print the pointer value and skip accessing metadata.
Fixes: 81819f0fc828 ("SLUB core")
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Li Qiong <liqiong(a)nfschina.com>
---
v2:
- rephrase the commit message, add comment for object_err().
v3:
- check object pointer in object_err().
v4:
- restore changes in alloc_consistency_checks().
v5:
- rephrase message, fix code style.
v6:
- add checking 'object' if NULL.
---
mm/slub.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/mm/slub.c b/mm/slub.c
index 31e11ef256f9..972cf2bb2ee6 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1104,7 +1104,12 @@ static void object_err(struct kmem_cache *s, struct slab *slab,
return;
slab_bug(s, reason);
- print_trailer(s, slab, object);
+ if (!object || !check_valid_pointer(s, slab, object)) {
+ print_slab_info(slab);
+ pr_err("Invalid pointer 0x%p\n", object);
+ } else {
+ print_trailer(s, slab, object);
+ }
add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
WARN_ON(1);
--
2.30.2
acpi_put_table() is only called when kobject_create_and_add() or
fpdt_process_subtable() fails, but not on the success path. This causes
a memory leak if initialization succeeds.
Ensure acpi_put_table() is called in all cases by adding a put_table
label and routing both success and failure paths through it. Drop the
err_subtable label since kobject_put() is only needed when
fpdt_process_subtable() fails.
Fixes: d1eb86e59be0 ("ACPI: tables: introduce support for FPDT table")
Cc: stable(a)vger.kernel.org
Signed-off-by: Zhen Ni <zhen.ni(a)easystack.cn>
---
drivers/acpi/acpi_fpdt.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/drivers/acpi/acpi_fpdt.c b/drivers/acpi/acpi_fpdt.c
index 271092f2700a..c8aea5bb187c 100644
--- a/drivers/acpi/acpi_fpdt.c
+++ b/drivers/acpi/acpi_fpdt.c
@@ -275,7 +275,7 @@ static int __init acpi_init_fpdt(void)
struct acpi_table_header *header;
struct fpdt_subtable_entry *subtable;
u32 offset = sizeof(*header);
- int result;
+ int result = 0;
status = acpi_get_table(ACPI_SIG_FPDT, 0, &header);
@@ -285,7 +285,7 @@ static int __init acpi_init_fpdt(void)
fpdt_kobj = kobject_create_and_add("fpdt", acpi_kobj);
if (!fpdt_kobj) {
result = -ENOMEM;
- goto err_nomem;
+ goto put_table;
}
while (offset < header->length) {
@@ -295,8 +295,10 @@ static int __init acpi_init_fpdt(void)
case SUBTABLE_S3PT:
result = fpdt_process_subtable(subtable->address,
subtable->type);
- if (result)
- goto err_subtable;
+ if (result) {
+ kobject_put(fpdt_kobj);
+ goto put_table;
+ }
break;
default:
/* Other types are reserved in ACPI 6.4 spec. */
@@ -304,11 +306,8 @@ static int __init acpi_init_fpdt(void)
}
offset += sizeof(*subtable);
}
- return 0;
-err_subtable:
- kobject_put(fpdt_kobj);
-err_nomem:
+put_table:
acpi_put_table(header);
return result;
}
--
2.20.1
From: Jiufei Xue <jiufei.xue(a)samsung.com>
[ Upstream commit d02d2c98d25793902f65803ab853b592c7a96b29 ]
An use-after-free issue occurred when __mark_inode_dirty() get the
bdi_writeback that was in the progress of switching.
CPU: 1 PID: 562 Comm: systemd-random- Not tainted 6.6.56-gb4403bd46a8e #1
......
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __mark_inode_dirty+0x124/0x418
lr : __mark_inode_dirty+0x118/0x418
sp : ffffffc08c9dbbc0
........
Call trace:
__mark_inode_dirty+0x124/0x418
generic_update_time+0x4c/0x60
file_modified+0xcc/0xd0
ext4_buffered_write_iter+0x58/0x124
ext4_file_write_iter+0x54/0x704
vfs_write+0x1c0/0x308
ksys_write+0x74/0x10c
__arm64_sys_write+0x1c/0x28
invoke_syscall+0x48/0x114
el0_svc_common.constprop.0+0xc0/0xe0
do_el0_svc+0x1c/0x28
el0_svc+0x40/0xe4
el0t_64_sync_handler+0x120/0x12c
el0t_64_sync+0x194/0x198
Root cause is:
systemd-random-seed kworker
----------------------------------------------------------------------
___mark_inode_dirty inode_switch_wbs_work_fn
spin_lock(&inode->i_lock);
inode_attach_wb
locked_inode_to_wb_and_lock_list
get inode->i_wb
spin_unlock(&inode->i_lock);
spin_lock(&wb->list_lock)
spin_lock(&inode->i_lock)
inode_io_list_move_locked
spin_unlock(&wb->list_lock)
spin_unlock(&inode->i_lock)
spin_lock(&old_wb->list_lock)
inode_do_switch_wbs
spin_lock(&inode->i_lock)
inode->i_wb = new_wb
spin_unlock(&inode->i_lock)
spin_unlock(&old_wb->list_lock)
wb_put_many(old_wb, nr_switched)
cgwb_release
old wb released
wb_wakeup_delayed() accesses wb,
then trigger the use-after-free
issue
Fix this race condition by holding inode spinlock until
wb_wakeup_delayed() finished.
Signed-off-by: Jiufei Xue <jiufei.xue(a)samsung.com>
Link: https://lore.kernel.org/20250728100715.3863241-1-jiufei.xue@samsung.com
Reviewed-by: Jan Kara <jack(a)suse.cz>
Signed-off-by: Christian Brauner <brauner(a)kernel.org>
Signed-off-by: Sasha Levin <sashal(a)kernel.org>
---
LLM Generated explanations, may be completely bogus:
Based on my thorough analysis of the commit and the kernel code, here's
my assessment:
**Backport Status: YES**
## Extensive Explanation:
This commit fixes a **critical use-after-free vulnerability** in the
writeback subsystem that should definitely be backported to stable
kernel trees. Here's why:
### 1. **Real Security Bug with Clear Impact**
The commit fixes a genuine use-after-free vulnerability that occurs in
`__mark_inode_dirty()`. The bug manifests as a kernel crash with a clear
call trace showing memory corruption. This is not a theoretical issue -
it has been observed in production (kernel 6.6.56).
### 2. **Race Condition Details**
The race condition occurs between two concurrent operations:
- **Thread A** (`__mark_inode_dirty`): Gets a reference to
`inode->i_wb`, releases the inode lock, then calls
`wb_wakeup_delayed(wb)`
- **Thread B** (`inode_switch_wbs_work_fn`): Switches the inode's
writeback context, releases the old wb via `wb_put_many()`, which can
trigger `cgwb_release` and free the wb structure
The vulnerability window exists because Thread A accesses the wb
structure (`wb_wakeup_delayed(wb)`) after releasing the inode lock but
before completing its operation, while Thread B can free that same wb
structure in parallel.
### 3. **Minimal and Contained Fix**
The fix is remarkably simple and surgical - it only reorders lock
releases:
```c
- spin_unlock(&wb->list_lock);
- spin_unlock(&inode->i_lock);
- trace_writeback_dirty_inode_enqueue(inode);
-
if (wakeup_bdi && (wb->bdi->capabilities & BDI_CAP_WRITEBACK))
wb_wakeup_delayed(wb);
+
+ spin_unlock(&wb->list_lock);
+ spin_unlock(&inode->i_lock);
+ trace_writeback_dirty_inode_enqueue(inode);
```
The fix ensures that `wb_wakeup_delayed()` is called while still holding
the locks, preventing the wb from being freed during the operation. This
is a classic lock ordering fix with minimal code change (just moving 3
lines).
### 4. **Critical Subsystem**
The writeback subsystem is fundamental to filesystem operations - it
handles dirty page writeback, inode management, and I/O scheduling. A
use-after-free here can lead to:
- System crashes/panics
- Data corruption
- Security vulnerabilities (potential for exploitation)
### 5. **Matches Stable Criteria**
This fix perfectly aligns with stable kernel rules:
- **Fixes a real bug**: Documented use-after-free with crash trace
- **Already upstream**: Has been reviewed by Jan Kara (filesystem
maintainer) and merged by Christian Brauner
- **Small change**: Only 6 lines moved, no new logic
- **No new features**: Pure bug fix
- **Low regression risk**: Simply extends existing lock protection
slightly
### 6. **Similar Historical Fixes**
The git history shows multiple similar use-after-free fixes in this
subsystem have been backported:
- `f87904c07551` - writeback: avoid use-after-free after removing device
- `8e00c4e9dd85` - writeback: fix use-after-free in
finish_writeback_work()
- `614a4e377314` - writeback, cgroup: fix premature wb_put()
### 7. **CONFIG_CGROUP_WRITEBACK Dependency**
While this bug primarily affects systems with `CONFIG_CGROUP_WRITEBACK`
enabled (used for cgroup-aware writeback), this is a common
configuration in modern distributions, especially those using cgroups v2
for container workloads.
### 8. **No Side Effects**
The change has no functional side effects beyond fixing the race:
- The trace event still fires at the same logical point
- The wb_wakeup_delayed() still executes under the same conditions
- Only the lock hold duration is slightly extended to cover the wb
access
This is a textbook example of a commit that should be backported to
stable kernels - it fixes a serious bug with minimal, well-understood
changes in a critical subsystem.
fs/fs-writeback.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index cc57367fb641..a07b8cf73ae2 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -2608,10 +2608,6 @@ void __mark_inode_dirty(struct inode *inode, int flags)
wakeup_bdi = inode_io_list_move_locked(inode, wb,
dirty_list);
- spin_unlock(&wb->list_lock);
- spin_unlock(&inode->i_lock);
- trace_writeback_dirty_inode_enqueue(inode);
-
/*
* If this is the first dirty inode for this bdi,
* we have to wake-up the corresponding bdi thread
@@ -2621,6 +2617,11 @@ void __mark_inode_dirty(struct inode *inode, int flags)
if (wakeup_bdi &&
(wb->bdi->capabilities & BDI_CAP_WRITEBACK))
wb_wakeup_delayed(wb);
+
+ spin_unlock(&wb->list_lock);
+ spin_unlock(&inode->i_lock);
+ trace_writeback_dirty_inode_enqueue(inode);
+
return;
}
}
--
2.50.1
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 d8df126349dad855cdfedd6bbf315bad2e901c2f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025082517-crazily-renewed-62e6@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From d8df126349dad855cdfedd6bbf315bad2e901c2f Mon Sep 17 00:00:00 2001
From: Tianxiang Peng <txpeng(a)tencent.com>
Date: Mon, 23 Jun 2025 17:31:53 +0800
Subject: [PATCH] x86/cpu/hygon: Add missing resctrl_cpu_detect() in bsp_init
helper
Since
923f3a2b48bd ("x86/resctrl: Query LLC monitoring properties once during boot")
resctrl_cpu_detect() has been moved from common CPU initialization code to
the vendor-specific BSP init helper, while Hygon didn't put that call in their
code.
This triggers a division by zero fault during early booting stage on our
machines with X86_FEATURE_CQM* supported, where get_rdt_mon_resources() tries
to calculate mon_l3_config with uninitialized boot_cpu_data.x86_cache_occ_scale.
Add the missing resctrl_cpu_detect() in the Hygon BSP init helper.
[ bp: Massage commit message. ]
Fixes: 923f3a2b48bd ("x86/resctrl: Query LLC monitoring properties once during boot")
Signed-off-by: Tianxiang Peng <txpeng(a)tencent.com>
Signed-off-by: Borislav Petkov (AMD) <bp(a)alien8.de>
Reviewed-by: Hui Li <caelli(a)tencent.com>
Cc: <stable(a)kernel.org>
Link: https://lore.kernel.org/20250623093153.3016937-1-txpeng@tencent.com
diff --git a/arch/x86/kernel/cpu/hygon.c b/arch/x86/kernel/cpu/hygon.c
index 2154f12766fb..1fda6c3a2b65 100644
--- a/arch/x86/kernel/cpu/hygon.c
+++ b/arch/x86/kernel/cpu/hygon.c
@@ -16,6 +16,7 @@
#include <asm/spec-ctrl.h>
#include <asm/delay.h>
#include <asm/msr.h>
+#include <asm/resctrl.h>
#include "cpu.h"
@@ -117,6 +118,8 @@ static void bsp_init_hygon(struct cpuinfo_x86 *c)
x86_amd_ls_cfg_ssbd_mask = 1ULL << 10;
}
}
+
+ resctrl_cpu_detect(c);
}
static void early_init_hygon(struct cpuinfo_x86 *c)
`dma_free_coherent()` must only be called if the corresponding
`dma_alloc_coherent()` call has succeeded. Calling it when the allocation
fails leads to undefined behavior.
Add a check to ensure that the memory is only freed when the allocation
was successful.
Signed-off-by: Salah Triki <salah.triki(a)gmail.com>
Fixes: 71bcada88b0f3 ("edac: altera: Add Altera SDRAM EDAC support")
Cc: Markus Elfring <Markus.Elfring(a)web.de>
Cc: Dinh Nguyen <dinguyen(a)kernel.org>
Cc: Borislav Petkov <bp(a)alien8.de>
Cc: Tony Luck <tony.luck(a)intel.com>
Cc: James Morse <james.morse(a)arm.com>
Cc: Mauro Carvalho Chehab <mchehab(a)kernel.org>
Cc: Robert Richter <rric(a)kernel.org>
Cc: linux-edac(a)vger.kernel.org
Cc: linux-kernel(a)vger.kernel.org
Cc: stable(a)vger.kernel.org
---
drivers/edac/altera_edac.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/drivers/edac/altera_edac.c b/drivers/edac/altera_edac.c
index cae52c654a15..7685a8550d4b 100644
--- a/drivers/edac/altera_edac.c
+++ b/drivers/edac/altera_edac.c
@@ -128,7 +128,6 @@ static ssize_t altr_sdr_mc_err_inject_write(struct file *file,
ptemp = dma_alloc_coherent(mci->pdev, 16, &dma_handle, GFP_KERNEL);
if (!ptemp) {
- dma_free_coherent(mci->pdev, 16, ptemp, dma_handle);
edac_printk(KERN_ERR, EDAC_MC,
"Inject: Buffer Allocation error\n");
return -ENOMEM;
--
2.43.0
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 d8df126349dad855cdfedd6bbf315bad2e901c2f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025082517-cramp-prissy-ebff@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From d8df126349dad855cdfedd6bbf315bad2e901c2f Mon Sep 17 00:00:00 2001
From: Tianxiang Peng <txpeng(a)tencent.com>
Date: Mon, 23 Jun 2025 17:31:53 +0800
Subject: [PATCH] x86/cpu/hygon: Add missing resctrl_cpu_detect() in bsp_init
helper
Since
923f3a2b48bd ("x86/resctrl: Query LLC monitoring properties once during boot")
resctrl_cpu_detect() has been moved from common CPU initialization code to
the vendor-specific BSP init helper, while Hygon didn't put that call in their
code.
This triggers a division by zero fault during early booting stage on our
machines with X86_FEATURE_CQM* supported, where get_rdt_mon_resources() tries
to calculate mon_l3_config with uninitialized boot_cpu_data.x86_cache_occ_scale.
Add the missing resctrl_cpu_detect() in the Hygon BSP init helper.
[ bp: Massage commit message. ]
Fixes: 923f3a2b48bd ("x86/resctrl: Query LLC monitoring properties once during boot")
Signed-off-by: Tianxiang Peng <txpeng(a)tencent.com>
Signed-off-by: Borislav Petkov (AMD) <bp(a)alien8.de>
Reviewed-by: Hui Li <caelli(a)tencent.com>
Cc: <stable(a)kernel.org>
Link: https://lore.kernel.org/20250623093153.3016937-1-txpeng@tencent.com
diff --git a/arch/x86/kernel/cpu/hygon.c b/arch/x86/kernel/cpu/hygon.c
index 2154f12766fb..1fda6c3a2b65 100644
--- a/arch/x86/kernel/cpu/hygon.c
+++ b/arch/x86/kernel/cpu/hygon.c
@@ -16,6 +16,7 @@
#include <asm/spec-ctrl.h>
#include <asm/delay.h>
#include <asm/msr.h>
+#include <asm/resctrl.h>
#include "cpu.h"
@@ -117,6 +118,8 @@ static void bsp_init_hygon(struct cpuinfo_x86 *c)
x86_amd_ls_cfg_ssbd_mask = 1ULL << 10;
}
}
+
+ resctrl_cpu_detect(c);
}
static void early_init_hygon(struct cpuinfo_x86 *c)
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 d8df126349dad855cdfedd6bbf315bad2e901c2f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025082516-wikipedia-entitle-8772@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From d8df126349dad855cdfedd6bbf315bad2e901c2f Mon Sep 17 00:00:00 2001
From: Tianxiang Peng <txpeng(a)tencent.com>
Date: Mon, 23 Jun 2025 17:31:53 +0800
Subject: [PATCH] x86/cpu/hygon: Add missing resctrl_cpu_detect() in bsp_init
helper
Since
923f3a2b48bd ("x86/resctrl: Query LLC monitoring properties once during boot")
resctrl_cpu_detect() has been moved from common CPU initialization code to
the vendor-specific BSP init helper, while Hygon didn't put that call in their
code.
This triggers a division by zero fault during early booting stage on our
machines with X86_FEATURE_CQM* supported, where get_rdt_mon_resources() tries
to calculate mon_l3_config with uninitialized boot_cpu_data.x86_cache_occ_scale.
Add the missing resctrl_cpu_detect() in the Hygon BSP init helper.
[ bp: Massage commit message. ]
Fixes: 923f3a2b48bd ("x86/resctrl: Query LLC monitoring properties once during boot")
Signed-off-by: Tianxiang Peng <txpeng(a)tencent.com>
Signed-off-by: Borislav Petkov (AMD) <bp(a)alien8.de>
Reviewed-by: Hui Li <caelli(a)tencent.com>
Cc: <stable(a)kernel.org>
Link: https://lore.kernel.org/20250623093153.3016937-1-txpeng@tencent.com
diff --git a/arch/x86/kernel/cpu/hygon.c b/arch/x86/kernel/cpu/hygon.c
index 2154f12766fb..1fda6c3a2b65 100644
--- a/arch/x86/kernel/cpu/hygon.c
+++ b/arch/x86/kernel/cpu/hygon.c
@@ -16,6 +16,7 @@
#include <asm/spec-ctrl.h>
#include <asm/delay.h>
#include <asm/msr.h>
+#include <asm/resctrl.h>
#include "cpu.h"
@@ -117,6 +118,8 @@ static void bsp_init_hygon(struct cpuinfo_x86 *c)
x86_amd_ls_cfg_ssbd_mask = 1ULL << 10;
}
}
+
+ resctrl_cpu_detect(c);
}
static void early_init_hygon(struct cpuinfo_x86 *c)