If damon_call() is executed against a DAMON context that is not running,
the function returns error while keeping the damon_call_control object
linked to the context's call_controls list. Let's suppose the object is
deallocated after the damon_call(), and yet another damon_call() is
executed against the same context. The function tries to add the new
damon_call_control object to the call_controls list, which still has the
pointer to the previous damon_call_control object, which is deallocated.
As a result, use-after-free happens.
This can actually be triggered using the DAMON sysfs interface. It is
not easily exploitable since it requires the sysfs write permission and
making a definitely weird file writes, though. Please refer to the
report for more details about the issue reproduction steps.
Fix the issue by making damon_call() to cleanup the damon_call_control
object before returning the error.
Reported-by: JaeJoon Jung <rgbi3307(a)gmail.com>
Closes: https://lore.kernel.org/20251224094401.20384-1-rgbi3307@gmail.com
Fixes: 42b7491af14c ("mm/damon/core: introduce damon_call()")
Cc: <stable(a)vger.kernel.org> # 6.14.x
Signed-off-by: SeongJae Park <sj(a)kernel.org>
---
mm/damon/core.c | 31 ++++++++++++++++++++++++++++++-
1 file changed, 30 insertions(+), 1 deletion(-)
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 2d3e8006db50..65482a0ce20b 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1442,6 +1442,35 @@ bool damon_is_running(struct damon_ctx *ctx)
return running;
}
+/*
+ * damon_call_handle_inactive_ctx() - handle DAMON call request that added to
+ * an inactive context.
+ * @ctx: The inactive DAMON context.
+ * @control: Control variable of the call request.
+ *
+ * This function is called in a case that @control is added to @ctx but @ctx is
+ * not running (inactive). See if @ctx handled @control or not, and cleanup
+ * @control if it was not handled.
+ *
+ * Returns 0 if @control was handled by @ctx, negative error code otherwise.
+ */
+static int damon_call_handle_inactive_ctx(
+ struct damon_ctx *ctx, struct damon_call_control *control)
+{
+ struct damon_call_control *c;
+
+ mutex_lock(&ctx->call_controls_lock);
+ list_for_each_entry(c, &ctx->call_controls, list) {
+ if (c == control) {
+ list_del(&control->list);
+ mutex_unlock(&ctx->call_controls_lock);
+ return -EINVAL;
+ }
+ }
+ mutex_unlock(&ctx->call_controls_lock);
+ return 0;
+}
+
/**
* damon_call() - Invoke a given function on DAMON worker thread (kdamond).
* @ctx: DAMON context to call the function for.
@@ -1472,7 +1501,7 @@ int damon_call(struct damon_ctx *ctx, struct damon_call_control *control)
list_add_tail(&control->list, &ctx->call_controls);
mutex_unlock(&ctx->call_controls_lock);
if (!damon_is_running(ctx))
- return -EINVAL;
+ return damon_call_handle_inactive_ctx(ctx, control);
if (control->repeat)
return 0;
wait_for_completion(&control->completion);
base-commit: a100272b3541cb00a5e29fdc16e428234ebfddd1
--
2.47.3
The patch below does not apply to the 5.10-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-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x ee5a977b4e771cc181f39d504426dbd31ed701cc
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122959-unawake-devious-8898@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ee5a977b4e771cc181f39d504426dbd31ed701cc Mon Sep 17 00:00:00 2001
From: Fedor Pchelkin <pchelkin(a)ispras.ru>
Date: Sat, 1 Nov 2025 19:04:28 +0300
Subject: [PATCH] ext4: fix string copying in parse_apply_sb_mount_options()
strscpy_pad() can't be used to copy a non-NUL-term string into a NUL-term
string of possibly bigger size. Commit 0efc5990bca5 ("string.h: Introduce
memtostr() and memtostr_pad()") provides additional information in that
regard. So if this happens, the following warning is observed:
strnlen: detected buffer overflow: 65 byte read of buffer size 64
WARNING: CPU: 0 PID: 28655 at lib/string_helpers.c:1032 __fortify_report+0x96/0xc0 lib/string_helpers.c:1032
Modules linked in:
CPU: 0 UID: 0 PID: 28655 Comm: syz-executor.3 Not tainted 6.12.54-syzkaller-00144-g5f0270f1ba00 #0
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__fortify_report+0x96/0xc0 lib/string_helpers.c:1032
Call Trace:
<TASK>
__fortify_panic+0x1f/0x30 lib/string_helpers.c:1039
strnlen include/linux/fortify-string.h:235 [inline]
sized_strscpy include/linux/fortify-string.h:309 [inline]
parse_apply_sb_mount_options fs/ext4/super.c:2504 [inline]
__ext4_fill_super fs/ext4/super.c:5261 [inline]
ext4_fill_super+0x3c35/0xad00 fs/ext4/super.c:5706
get_tree_bdev_flags+0x387/0x620 fs/super.c:1636
vfs_get_tree+0x93/0x380 fs/super.c:1814
do_new_mount fs/namespace.c:3553 [inline]
path_mount+0x6ae/0x1f70 fs/namespace.c:3880
do_mount fs/namespace.c:3893 [inline]
__do_sys_mount fs/namespace.c:4103 [inline]
__se_sys_mount fs/namespace.c:4080 [inline]
__x64_sys_mount+0x280/0x300 fs/namespace.c:4080
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x64/0x140 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Since userspace is expected to provide s_mount_opts field to be at most 63
characters long with the ending byte being NUL-term, use a 64-byte buffer
which matches the size of s_mount_opts, so that strscpy_pad() does its job
properly. Return with error if the user still managed to provide a
non-NUL-term string here.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Fixes: 8ecb790ea8c3 ("ext4: avoid potential buffer over-read in parse_apply_sb_mount_options()")
Cc: stable(a)vger.kernel.org
Signed-off-by: Fedor Pchelkin <pchelkin(a)ispras.ru>
Reviewed-by: Baokun Li <libaokun1(a)huawei.com>
Reviewed-by: Jan Kara <jack(a)suse.cz>
Message-ID: <20251101160430.222297-1-pchelkin(a)ispras.ru>
Signed-off-by: Theodore Ts'o <tytso(a)mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7de15249e826..d1ba894c0e0a 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2476,7 +2476,7 @@ static int parse_apply_sb_mount_options(struct super_block *sb,
struct ext4_fs_context *m_ctx)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
- char s_mount_opts[65];
+ char s_mount_opts[64];
struct ext4_fs_context *s_ctx = NULL;
struct fs_context *fc = NULL;
int ret = -ENOMEM;
@@ -2484,7 +2484,8 @@ static int parse_apply_sb_mount_options(struct super_block *sb,
if (!sbi->s_es->s_mount_opts[0])
return 0;
- strscpy_pad(s_mount_opts, sbi->s_es->s_mount_opts);
+ if (strscpy_pad(s_mount_opts, sbi->s_es->s_mount_opts) < 0)
+ return -E2BIG;
fc = kzalloc(sizeof(struct fs_context), GFP_KERNEL);
if (!fc)
When starting multi-core loongarch virtualization on loongarch physical
machine, loading livepatch on the physical machine will cause an error
similar to the following:
[ 411.686289] livepatch: klp_try_switch_task: CPU 31/KVM:3116 has an
unreliable stack
The specific test steps are as follows:
1.Start a multi-core virtual machine on a physical machine
2.Enter the following command on the physical machine to turn on the debug
switch:
echo "file kernel/livepatch/transition.c +p" > /sys/kernel/debug/\
dynamic_debug/control
3.Load livepatch:
modprobe livepatch-sample
Through the above steps, similar prints can be viewed in dmesg.
The reason for this issue is that the code of the kvm_exc_entry function
was copied in the function kvm_loongarch_env_init. When the cpu needs to
execute kvm_exc_entry, it will switch to the copied address for execution.
The new address of the kvm_exc_entry function cannot be recognized in ORC,
which eventually leads to the arch_stack_walk_reliable function returning
an error and printing an exception message.
To solve the above problems, we directly compile the switch.S file into
the kernel instead of the module. In this way, the function kvm_exc_entry
will no longer need to be copied.
changlog:
V3<-V2:
1.Replace the EXPORT_SYMBOL macro declaration symbol with the
EXPORT_SYMBOL_FOR_KVM macro
2.Add some comments in kvm_enter_guest
3.Place the correct pc address in era
4.Move .p2align after .text
V2<-V1:
1.Rollback the modification of function parameter types such as
kvm_save_fpu. In the asm-prototypes.h header file, only the parameter types
it depends on are included
Cc: Huacai Chen <chenhuacai(a)kernel.org>
Cc: WANG Xuerui <kernel(a)xen0n.name>
Cc: Tianrui Zhao <zhaotianrui(a)loongson.cn>
Cc: Bibo Mao <maobibo(a)loongson.cn>
Cc: Charlie Jenkins <charlie(a)rivosinc.com>
Cc: Xianglai Li <lixianglai(a)loongson.cn>
Cc: Thomas Gleixner <tglx(a)linutronix.de>
Cc: stable(a)vger.kernel.org
Cc: Tiezhu Yang <yangtiezhu(a)loongson.cn>
Xianglai Li (2):
LoongArch: KVM: Compile the switch.S file directly into the kernel
LoongArch: KVM: fix "unreliable stack" issue
arch/loongarch/Kbuild | 2 +-
arch/loongarch/include/asm/asm-prototypes.h | 21 +++++++++++++
arch/loongarch/include/asm/kvm_host.h | 3 --
arch/loongarch/kvm/Makefile | 2 +-
arch/loongarch/kvm/main.c | 35 ++-------------------
arch/loongarch/kvm/switch.S | 32 ++++++++++++++++---
6 files changed, 53 insertions(+), 42 deletions(-)
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
--
2.39.1
The patch below does not apply to the 5.10-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-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 6abfe107894af7e8ce3a2e120c619d81ee764ad5
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122936-jaunt-sliding-0a13@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 6abfe107894af7e8ce3a2e120c619d81ee764ad5 Mon Sep 17 00:00:00 2001
From: Ye Bin <yebin10(a)huawei.com>
Date: Mon, 3 Nov 2025 09:01:23 +0800
Subject: [PATCH] jbd2: fix the inconsistency between checksum and data in
memory for journal sb
Copying the file system while it is mounted as read-only results in
a mount failure:
[~]# mkfs.ext4 -F /dev/sdc
[~]# mount /dev/sdc -o ro /mnt/test
[~]# dd if=/dev/sdc of=/dev/sda bs=1M
[~]# mount /dev/sda /mnt/test1
[ 1094.849826] JBD2: journal checksum error
[ 1094.850927] EXT4-fs (sda): Could not load journal inode
mount: mount /dev/sda on /mnt/test1 failed: Bad message
The process described above is just an abstracted way I came up with to
reproduce the issue. In the actual scenario, the file system was mounted
read-only and then copied while it was still mounted. It was found that
the mount operation failed. The user intended to verify the data or use
it as a backup, and this action was performed during a version upgrade.
Above issue may happen as follows:
ext4_fill_super
set_journal_csum_feature_set(sb)
if (ext4_has_metadata_csum(sb))
incompat = JBD2_FEATURE_INCOMPAT_CSUM_V3;
if (test_opt(sb, JOURNAL_CHECKSUM)
jbd2_journal_set_features(sbi->s_journal, compat, 0, incompat);
lock_buffer(journal->j_sb_buffer);
sb->s_feature_incompat |= cpu_to_be32(incompat);
//The data in the journal sb was modified, but the checksum was not
updated, so the data remaining in memory has a mismatch between the
data and the checksum.
unlock_buffer(journal->j_sb_buffer);
In this case, the journal sb copied over is in a state where the checksum
and data are inconsistent, so mounting fails.
To solve the above issue, update the checksum in memory after modifying
the journal sb.
Fixes: 4fd5ea43bc11 ("jbd2: checksum journal superblock")
Signed-off-by: Ye Bin <yebin10(a)huawei.com>
Reviewed-by: Baokun Li <libaokun1(a)huawei.com>
Reviewed-by: Darrick J. Wong <djwong(a)kernel.org>
Reviewed-by: Jan Kara <jack(a)suse.cz>
Message-ID: <20251103010123.3753631-1-yebin(a)huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso(a)mit.edu>
Cc: stable(a)kernel.org
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 2fe1786a8f1b..c973162d5b31 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -2354,6 +2354,12 @@ int jbd2_journal_set_features(journal_t *journal, unsigned long compat,
sb->s_feature_compat |= cpu_to_be32(compat);
sb->s_feature_ro_compat |= cpu_to_be32(ro);
sb->s_feature_incompat |= cpu_to_be32(incompat);
+ /*
+ * Update the checksum now so that it is valid even for read-only
+ * filesystems where jbd2_write_superblock() doesn't get called.
+ */
+ if (jbd2_journal_has_csum_v2or3(journal))
+ sb->s_checksum = jbd2_superblock_csum(sb);
unlock_buffer(journal->j_sb_buffer);
jbd2_journal_init_transaction_limits(journal);
@@ -2383,9 +2389,17 @@ void jbd2_journal_clear_features(journal_t *journal, unsigned long compat,
sb = journal->j_superblock;
+ lock_buffer(journal->j_sb_buffer);
sb->s_feature_compat &= ~cpu_to_be32(compat);
sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
sb->s_feature_incompat &= ~cpu_to_be32(incompat);
+ /*
+ * Update the checksum now so that it is valid even for read-only
+ * filesystems where jbd2_write_superblock() doesn't get called.
+ */
+ if (jbd2_journal_has_csum_v2or3(journal))
+ sb->s_checksum = jbd2_superblock_csum(sb);
+ unlock_buffer(journal->j_sb_buffer);
jbd2_journal_init_transaction_limits(journal);
}
EXPORT_SYMBOL(jbd2_journal_clear_features);
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 6abfe107894af7e8ce3a2e120c619d81ee764ad5
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122935-turban-sweep-c818@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 6abfe107894af7e8ce3a2e120c619d81ee764ad5 Mon Sep 17 00:00:00 2001
From: Ye Bin <yebin10(a)huawei.com>
Date: Mon, 3 Nov 2025 09:01:23 +0800
Subject: [PATCH] jbd2: fix the inconsistency between checksum and data in
memory for journal sb
Copying the file system while it is mounted as read-only results in
a mount failure:
[~]# mkfs.ext4 -F /dev/sdc
[~]# mount /dev/sdc -o ro /mnt/test
[~]# dd if=/dev/sdc of=/dev/sda bs=1M
[~]# mount /dev/sda /mnt/test1
[ 1094.849826] JBD2: journal checksum error
[ 1094.850927] EXT4-fs (sda): Could not load journal inode
mount: mount /dev/sda on /mnt/test1 failed: Bad message
The process described above is just an abstracted way I came up with to
reproduce the issue. In the actual scenario, the file system was mounted
read-only and then copied while it was still mounted. It was found that
the mount operation failed. The user intended to verify the data or use
it as a backup, and this action was performed during a version upgrade.
Above issue may happen as follows:
ext4_fill_super
set_journal_csum_feature_set(sb)
if (ext4_has_metadata_csum(sb))
incompat = JBD2_FEATURE_INCOMPAT_CSUM_V3;
if (test_opt(sb, JOURNAL_CHECKSUM)
jbd2_journal_set_features(sbi->s_journal, compat, 0, incompat);
lock_buffer(journal->j_sb_buffer);
sb->s_feature_incompat |= cpu_to_be32(incompat);
//The data in the journal sb was modified, but the checksum was not
updated, so the data remaining in memory has a mismatch between the
data and the checksum.
unlock_buffer(journal->j_sb_buffer);
In this case, the journal sb copied over is in a state where the checksum
and data are inconsistent, so mounting fails.
To solve the above issue, update the checksum in memory after modifying
the journal sb.
Fixes: 4fd5ea43bc11 ("jbd2: checksum journal superblock")
Signed-off-by: Ye Bin <yebin10(a)huawei.com>
Reviewed-by: Baokun Li <libaokun1(a)huawei.com>
Reviewed-by: Darrick J. Wong <djwong(a)kernel.org>
Reviewed-by: Jan Kara <jack(a)suse.cz>
Message-ID: <20251103010123.3753631-1-yebin(a)huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso(a)mit.edu>
Cc: stable(a)kernel.org
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 2fe1786a8f1b..c973162d5b31 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -2354,6 +2354,12 @@ int jbd2_journal_set_features(journal_t *journal, unsigned long compat,
sb->s_feature_compat |= cpu_to_be32(compat);
sb->s_feature_ro_compat |= cpu_to_be32(ro);
sb->s_feature_incompat |= cpu_to_be32(incompat);
+ /*
+ * Update the checksum now so that it is valid even for read-only
+ * filesystems where jbd2_write_superblock() doesn't get called.
+ */
+ if (jbd2_journal_has_csum_v2or3(journal))
+ sb->s_checksum = jbd2_superblock_csum(sb);
unlock_buffer(journal->j_sb_buffer);
jbd2_journal_init_transaction_limits(journal);
@@ -2383,9 +2389,17 @@ void jbd2_journal_clear_features(journal_t *journal, unsigned long compat,
sb = journal->j_superblock;
+ lock_buffer(journal->j_sb_buffer);
sb->s_feature_compat &= ~cpu_to_be32(compat);
sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
sb->s_feature_incompat &= ~cpu_to_be32(incompat);
+ /*
+ * Update the checksum now so that it is valid even for read-only
+ * filesystems where jbd2_write_superblock() doesn't get called.
+ */
+ if (jbd2_journal_has_csum_v2or3(journal))
+ sb->s_checksum = jbd2_superblock_csum(sb);
+ unlock_buffer(journal->j_sb_buffer);
jbd2_journal_init_transaction_limits(journal);
}
EXPORT_SYMBOL(jbd2_journal_clear_features);
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 ee5a977b4e771cc181f39d504426dbd31ed701cc
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122957-crevice-busily-7e0e@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ee5a977b4e771cc181f39d504426dbd31ed701cc Mon Sep 17 00:00:00 2001
From: Fedor Pchelkin <pchelkin(a)ispras.ru>
Date: Sat, 1 Nov 2025 19:04:28 +0300
Subject: [PATCH] ext4: fix string copying in parse_apply_sb_mount_options()
strscpy_pad() can't be used to copy a non-NUL-term string into a NUL-term
string of possibly bigger size. Commit 0efc5990bca5 ("string.h: Introduce
memtostr() and memtostr_pad()") provides additional information in that
regard. So if this happens, the following warning is observed:
strnlen: detected buffer overflow: 65 byte read of buffer size 64
WARNING: CPU: 0 PID: 28655 at lib/string_helpers.c:1032 __fortify_report+0x96/0xc0 lib/string_helpers.c:1032
Modules linked in:
CPU: 0 UID: 0 PID: 28655 Comm: syz-executor.3 Not tainted 6.12.54-syzkaller-00144-g5f0270f1ba00 #0
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__fortify_report+0x96/0xc0 lib/string_helpers.c:1032
Call Trace:
<TASK>
__fortify_panic+0x1f/0x30 lib/string_helpers.c:1039
strnlen include/linux/fortify-string.h:235 [inline]
sized_strscpy include/linux/fortify-string.h:309 [inline]
parse_apply_sb_mount_options fs/ext4/super.c:2504 [inline]
__ext4_fill_super fs/ext4/super.c:5261 [inline]
ext4_fill_super+0x3c35/0xad00 fs/ext4/super.c:5706
get_tree_bdev_flags+0x387/0x620 fs/super.c:1636
vfs_get_tree+0x93/0x380 fs/super.c:1814
do_new_mount fs/namespace.c:3553 [inline]
path_mount+0x6ae/0x1f70 fs/namespace.c:3880
do_mount fs/namespace.c:3893 [inline]
__do_sys_mount fs/namespace.c:4103 [inline]
__se_sys_mount fs/namespace.c:4080 [inline]
__x64_sys_mount+0x280/0x300 fs/namespace.c:4080
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x64/0x140 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Since userspace is expected to provide s_mount_opts field to be at most 63
characters long with the ending byte being NUL-term, use a 64-byte buffer
which matches the size of s_mount_opts, so that strscpy_pad() does its job
properly. Return with error if the user still managed to provide a
non-NUL-term string here.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Fixes: 8ecb790ea8c3 ("ext4: avoid potential buffer over-read in parse_apply_sb_mount_options()")
Cc: stable(a)vger.kernel.org
Signed-off-by: Fedor Pchelkin <pchelkin(a)ispras.ru>
Reviewed-by: Baokun Li <libaokun1(a)huawei.com>
Reviewed-by: Jan Kara <jack(a)suse.cz>
Message-ID: <20251101160430.222297-1-pchelkin(a)ispras.ru>
Signed-off-by: Theodore Ts'o <tytso(a)mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7de15249e826..d1ba894c0e0a 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2476,7 +2476,7 @@ static int parse_apply_sb_mount_options(struct super_block *sb,
struct ext4_fs_context *m_ctx)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
- char s_mount_opts[65];
+ char s_mount_opts[64];
struct ext4_fs_context *s_ctx = NULL;
struct fs_context *fc = NULL;
int ret = -ENOMEM;
@@ -2484,7 +2484,8 @@ static int parse_apply_sb_mount_options(struct super_block *sb,
if (!sbi->s_es->s_mount_opts[0])
return 0;
- strscpy_pad(s_mount_opts, sbi->s_es->s_mount_opts);
+ if (strscpy_pad(s_mount_opts, sbi->s_es->s_mount_opts) < 0)
+ return -E2BIG;
fc = kzalloc(sizeof(struct fs_context), GFP_KERNEL);
if (!fc)
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 ee5a977b4e771cc181f39d504426dbd31ed701cc
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122956-dropkick-outlast-5a49@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ee5a977b4e771cc181f39d504426dbd31ed701cc Mon Sep 17 00:00:00 2001
From: Fedor Pchelkin <pchelkin(a)ispras.ru>
Date: Sat, 1 Nov 2025 19:04:28 +0300
Subject: [PATCH] ext4: fix string copying in parse_apply_sb_mount_options()
strscpy_pad() can't be used to copy a non-NUL-term string into a NUL-term
string of possibly bigger size. Commit 0efc5990bca5 ("string.h: Introduce
memtostr() and memtostr_pad()") provides additional information in that
regard. So if this happens, the following warning is observed:
strnlen: detected buffer overflow: 65 byte read of buffer size 64
WARNING: CPU: 0 PID: 28655 at lib/string_helpers.c:1032 __fortify_report+0x96/0xc0 lib/string_helpers.c:1032
Modules linked in:
CPU: 0 UID: 0 PID: 28655 Comm: syz-executor.3 Not tainted 6.12.54-syzkaller-00144-g5f0270f1ba00 #0
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__fortify_report+0x96/0xc0 lib/string_helpers.c:1032
Call Trace:
<TASK>
__fortify_panic+0x1f/0x30 lib/string_helpers.c:1039
strnlen include/linux/fortify-string.h:235 [inline]
sized_strscpy include/linux/fortify-string.h:309 [inline]
parse_apply_sb_mount_options fs/ext4/super.c:2504 [inline]
__ext4_fill_super fs/ext4/super.c:5261 [inline]
ext4_fill_super+0x3c35/0xad00 fs/ext4/super.c:5706
get_tree_bdev_flags+0x387/0x620 fs/super.c:1636
vfs_get_tree+0x93/0x380 fs/super.c:1814
do_new_mount fs/namespace.c:3553 [inline]
path_mount+0x6ae/0x1f70 fs/namespace.c:3880
do_mount fs/namespace.c:3893 [inline]
__do_sys_mount fs/namespace.c:4103 [inline]
__se_sys_mount fs/namespace.c:4080 [inline]
__x64_sys_mount+0x280/0x300 fs/namespace.c:4080
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x64/0x140 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Since userspace is expected to provide s_mount_opts field to be at most 63
characters long with the ending byte being NUL-term, use a 64-byte buffer
which matches the size of s_mount_opts, so that strscpy_pad() does its job
properly. Return with error if the user still managed to provide a
non-NUL-term string here.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Fixes: 8ecb790ea8c3 ("ext4: avoid potential buffer over-read in parse_apply_sb_mount_options()")
Cc: stable(a)vger.kernel.org
Signed-off-by: Fedor Pchelkin <pchelkin(a)ispras.ru>
Reviewed-by: Baokun Li <libaokun1(a)huawei.com>
Reviewed-by: Jan Kara <jack(a)suse.cz>
Message-ID: <20251101160430.222297-1-pchelkin(a)ispras.ru>
Signed-off-by: Theodore Ts'o <tytso(a)mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7de15249e826..d1ba894c0e0a 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2476,7 +2476,7 @@ static int parse_apply_sb_mount_options(struct super_block *sb,
struct ext4_fs_context *m_ctx)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
- char s_mount_opts[65];
+ char s_mount_opts[64];
struct ext4_fs_context *s_ctx = NULL;
struct fs_context *fc = NULL;
int ret = -ENOMEM;
@@ -2484,7 +2484,8 @@ static int parse_apply_sb_mount_options(struct super_block *sb,
if (!sbi->s_es->s_mount_opts[0])
return 0;
- strscpy_pad(s_mount_opts, sbi->s_es->s_mount_opts);
+ if (strscpy_pad(s_mount_opts, sbi->s_es->s_mount_opts) < 0)
+ return -E2BIG;
fc = kzalloc(sizeof(struct fs_context), GFP_KERNEL);
if (!fc)
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 6abfe107894af7e8ce3a2e120c619d81ee764ad5
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122934-exclude-sevenfold-d418@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 6abfe107894af7e8ce3a2e120c619d81ee764ad5 Mon Sep 17 00:00:00 2001
From: Ye Bin <yebin10(a)huawei.com>
Date: Mon, 3 Nov 2025 09:01:23 +0800
Subject: [PATCH] jbd2: fix the inconsistency between checksum and data in
memory for journal sb
Copying the file system while it is mounted as read-only results in
a mount failure:
[~]# mkfs.ext4 -F /dev/sdc
[~]# mount /dev/sdc -o ro /mnt/test
[~]# dd if=/dev/sdc of=/dev/sda bs=1M
[~]# mount /dev/sda /mnt/test1
[ 1094.849826] JBD2: journal checksum error
[ 1094.850927] EXT4-fs (sda): Could not load journal inode
mount: mount /dev/sda on /mnt/test1 failed: Bad message
The process described above is just an abstracted way I came up with to
reproduce the issue. In the actual scenario, the file system was mounted
read-only and then copied while it was still mounted. It was found that
the mount operation failed. The user intended to verify the data or use
it as a backup, and this action was performed during a version upgrade.
Above issue may happen as follows:
ext4_fill_super
set_journal_csum_feature_set(sb)
if (ext4_has_metadata_csum(sb))
incompat = JBD2_FEATURE_INCOMPAT_CSUM_V3;
if (test_opt(sb, JOURNAL_CHECKSUM)
jbd2_journal_set_features(sbi->s_journal, compat, 0, incompat);
lock_buffer(journal->j_sb_buffer);
sb->s_feature_incompat |= cpu_to_be32(incompat);
//The data in the journal sb was modified, but the checksum was not
updated, so the data remaining in memory has a mismatch between the
data and the checksum.
unlock_buffer(journal->j_sb_buffer);
In this case, the journal sb copied over is in a state where the checksum
and data are inconsistent, so mounting fails.
To solve the above issue, update the checksum in memory after modifying
the journal sb.
Fixes: 4fd5ea43bc11 ("jbd2: checksum journal superblock")
Signed-off-by: Ye Bin <yebin10(a)huawei.com>
Reviewed-by: Baokun Li <libaokun1(a)huawei.com>
Reviewed-by: Darrick J. Wong <djwong(a)kernel.org>
Reviewed-by: Jan Kara <jack(a)suse.cz>
Message-ID: <20251103010123.3753631-1-yebin(a)huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso(a)mit.edu>
Cc: stable(a)kernel.org
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 2fe1786a8f1b..c973162d5b31 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -2354,6 +2354,12 @@ int jbd2_journal_set_features(journal_t *journal, unsigned long compat,
sb->s_feature_compat |= cpu_to_be32(compat);
sb->s_feature_ro_compat |= cpu_to_be32(ro);
sb->s_feature_incompat |= cpu_to_be32(incompat);
+ /*
+ * Update the checksum now so that it is valid even for read-only
+ * filesystems where jbd2_write_superblock() doesn't get called.
+ */
+ if (jbd2_journal_has_csum_v2or3(journal))
+ sb->s_checksum = jbd2_superblock_csum(sb);
unlock_buffer(journal->j_sb_buffer);
jbd2_journal_init_transaction_limits(journal);
@@ -2383,9 +2389,17 @@ void jbd2_journal_clear_features(journal_t *journal, unsigned long compat,
sb = journal->j_superblock;
+ lock_buffer(journal->j_sb_buffer);
sb->s_feature_compat &= ~cpu_to_be32(compat);
sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
sb->s_feature_incompat &= ~cpu_to_be32(incompat);
+ /*
+ * Update the checksum now so that it is valid even for read-only
+ * filesystems where jbd2_write_superblock() doesn't get called.
+ */
+ if (jbd2_journal_has_csum_v2or3(journal))
+ sb->s_checksum = jbd2_superblock_csum(sb);
+ unlock_buffer(journal->j_sb_buffer);
jbd2_journal_init_transaction_limits(journal);
}
EXPORT_SYMBOL(jbd2_journal_clear_features);