* [PATCH] ext4: fix null-ptr-deref in ext4_write_info
@ 2022-08-05 12:39 Baokun Li
2022-08-05 13:07 ` Lukas Czerner
2022-09-27 21:53 ` Theodore Ts'o
0 siblings, 2 replies; 5+ messages in thread
From: Baokun Li @ 2022-08-05 12:39 UTC (permalink / raw)
To: linux-ext4
Cc: tytso, adilger.kernel, jack, ritesh.list, lczerner, enwlinux,
linux-kernel, yi.zhang, yebin10, yukuai3, libaokun1
I caught a null-ptr-deref bug as follows:
==================================================================
KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
CPU: 1 PID: 1589 Comm: umount Not tainted 5.10.0-02219-dirty #339
RIP: 0010:ext4_write_info+0x53/0x1b0
[...]
Call Trace:
dquot_writeback_dquots+0x341/0x9a0
ext4_sync_fs+0x19e/0x800
__sync_filesystem+0x83/0x100
sync_filesystem+0x89/0xf0
generic_shutdown_super+0x79/0x3e0
kill_block_super+0xa1/0x110
deactivate_locked_super+0xac/0x130
deactivate_super+0xb6/0xd0
cleanup_mnt+0x289/0x400
__cleanup_mnt+0x16/0x20
task_work_run+0x11c/0x1c0
exit_to_user_mode_prepare+0x203/0x210
syscall_exit_to_user_mode+0x5b/0x3a0
do_syscall_64+0x59/0x70
entry_SYSCALL_64_after_hwframe+0x44/0xa9
==================================================================
Above issue may happen as follows:
-------------------------------------
exit_to_user_mode_prepare
task_work_run
__cleanup_mnt
cleanup_mnt
deactivate_super
deactivate_locked_super
kill_block_super
generic_shutdown_super
shrink_dcache_for_umount
dentry = sb->s_root
sb->s_root = NULL <--- Here set NULL
sync_filesystem
__sync_filesystem
sb->s_op->sync_fs > ext4_sync_fs
dquot_writeback_dquots
sb->dq_op->write_info > ext4_write_info
ext4_journal_start(d_inode(sb->s_root), EXT4_HT_QUOTA, 2)
d_inode(sb->s_root)
s_root->d_inode <--- Null pointer dereference
To solve this problem, we use ext4_journal_start_sb directly
to avoid s_root being used.
Signed-off-by: Baokun Li <libaokun1@huawei.com>
---
fs/ext4/super.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9a66abcca1a8..0ce4565422f6 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -6653,7 +6653,7 @@ static int ext4_write_info(struct super_block *sb, int type)
handle_t *handle;
/* Data block + inode block */
- handle = ext4_journal_start(d_inode(sb->s_root), EXT4_HT_QUOTA, 2);
+ handle = ext4_journal_start_sb(sb, EXT4_HT_QUOTA, 2);
if (IS_ERR(handle))
return PTR_ERR(handle);
ret = dquot_commit_info(sb, type);
--
2.31.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] ext4: fix null-ptr-deref in ext4_write_info
2022-08-05 12:39 [PATCH] ext4: fix null-ptr-deref in ext4_write_info Baokun Li
@ 2022-08-05 13:07 ` Lukas Czerner
2022-08-10 7:20 ` Baokun Li
2022-09-27 21:53 ` Theodore Ts'o
1 sibling, 1 reply; 5+ messages in thread
From: Lukas Czerner @ 2022-08-05 13:07 UTC (permalink / raw)
To: Baokun Li
Cc: linux-ext4, tytso, adilger.kernel, jack, ritesh.list, enwlinux,
linux-kernel, yi.zhang, yebin10, yukuai3
On Fri, Aug 05, 2022 at 08:39:47PM +0800, Baokun Li wrote:
> I caught a null-ptr-deref bug as follows:
> ==================================================================
> KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
> CPU: 1 PID: 1589 Comm: umount Not tainted 5.10.0-02219-dirty #339
> RIP: 0010:ext4_write_info+0x53/0x1b0
> [...]
> Call Trace:
> dquot_writeback_dquots+0x341/0x9a0
> ext4_sync_fs+0x19e/0x800
> __sync_filesystem+0x83/0x100
> sync_filesystem+0x89/0xf0
> generic_shutdown_super+0x79/0x3e0
> kill_block_super+0xa1/0x110
> deactivate_locked_super+0xac/0x130
> deactivate_super+0xb6/0xd0
> cleanup_mnt+0x289/0x400
> __cleanup_mnt+0x16/0x20
> task_work_run+0x11c/0x1c0
> exit_to_user_mode_prepare+0x203/0x210
> syscall_exit_to_user_mode+0x5b/0x3a0
> do_syscall_64+0x59/0x70
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> ==================================================================
>
> Above issue may happen as follows:
> -------------------------------------
> exit_to_user_mode_prepare
> task_work_run
> __cleanup_mnt
> cleanup_mnt
> deactivate_super
> deactivate_locked_super
> kill_block_super
> generic_shutdown_super
> shrink_dcache_for_umount
> dentry = sb->s_root
> sb->s_root = NULL <--- Here set NULL
> sync_filesystem
> __sync_filesystem
> sb->s_op->sync_fs > ext4_sync_fs
> dquot_writeback_dquots
> sb->dq_op->write_info > ext4_write_info
> ext4_journal_start(d_inode(sb->s_root), EXT4_HT_QUOTA, 2)
> d_inode(sb->s_root)
> s_root->d_inode <--- Null pointer dereference
>
> To solve this problem, we use ext4_journal_start_sb directly
> to avoid s_root being used.
Are we syncing the file system after the superblock shutdown and getting
away with it? This does not look good. Do you have a reproducer?
Thanks!
-Lukas
>
> Signed-off-by: Baokun Li <libaokun1@huawei.com>
> ---
> fs/ext4/super.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 9a66abcca1a8..0ce4565422f6 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -6653,7 +6653,7 @@ static int ext4_write_info(struct super_block *sb, int type)
> handle_t *handle;
>
> /* Data block + inode block */
> - handle = ext4_journal_start(d_inode(sb->s_root), EXT4_HT_QUOTA, 2);
> + handle = ext4_journal_start_sb(sb, EXT4_HT_QUOTA, 2);
> if (IS_ERR(handle))
> return PTR_ERR(handle);
> ret = dquot_commit_info(sb, type);
> --
> 2.31.1
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] ext4: fix null-ptr-deref in ext4_write_info
2022-08-05 13:07 ` Lukas Czerner
@ 2022-08-10 7:20 ` Baokun Li
2022-08-15 15:34 ` Jan Kara
0 siblings, 1 reply; 5+ messages in thread
From: Baokun Li @ 2022-08-10 7:20 UTC (permalink / raw)
To: Lukas Czerner
Cc: linux-ext4, tytso, adilger.kernel, jack, ritesh.list, enwlinux,
linux-kernel, yi.zhang, yebin10, yukuai3, Baokun Li
在 2022/8/5 21:07, Lukas Czerner 写道:
> On Fri, Aug 05, 2022 at 08:39:47PM +0800, Baokun Li wrote:
>> I caught a null-ptr-deref bug as follows:
>> ==================================================================
>> KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
>> CPU: 1 PID: 1589 Comm: umount Not tainted 5.10.0-02219-dirty #339
>> RIP: 0010:ext4_write_info+0x53/0x1b0
>> [...]
>> Call Trace:
>> dquot_writeback_dquots+0x341/0x9a0
>> ext4_sync_fs+0x19e/0x800
>> __sync_filesystem+0x83/0x100
>> sync_filesystem+0x89/0xf0
>> generic_shutdown_super+0x79/0x3e0
>> kill_block_super+0xa1/0x110
>> deactivate_locked_super+0xac/0x130
>> deactivate_super+0xb6/0xd0
>> cleanup_mnt+0x289/0x400
>> __cleanup_mnt+0x16/0x20
>> task_work_run+0x11c/0x1c0
>> exit_to_user_mode_prepare+0x203/0x210
>> syscall_exit_to_user_mode+0x5b/0x3a0
>> do_syscall_64+0x59/0x70
>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>> ==================================================================
>>
>> Above issue may happen as follows:
>> -------------------------------------
>> exit_to_user_mode_prepare
>> task_work_run
>> __cleanup_mnt
>> cleanup_mnt
>> deactivate_super
>> deactivate_locked_super
>> kill_block_super
>> generic_shutdown_super
>> shrink_dcache_for_umount
>> dentry = sb->s_root
>> sb->s_root = NULL <--- Here set NULL
>> sync_filesystem
>> __sync_filesystem
>> sb->s_op->sync_fs > ext4_sync_fs
>> dquot_writeback_dquots
>> sb->dq_op->write_info > ext4_write_info
>> ext4_journal_start(d_inode(sb->s_root), EXT4_HT_QUOTA, 2)
>> d_inode(sb->s_root)
>> s_root->d_inode <--- Null pointer dereference
>>
>> To solve this problem, we use ext4_journal_start_sb directly
>> to avoid s_root being used.
> Are we syncing the file system after the superblock shutdown and getting
> away with it? This does not look good. Do you have a reproducer?
>
> Thanks!
> -Lukas
Hi, Lukas!
This problem is triggered by a pressure test when I reproduce another
problem.
So I didn't have the reproducer.
I looked at the error stack code and found that it seems there is
something wrong.
Moreover, it's really weird to write code like
"ext4_journal_start(d_inode(sb->s_root), ...)".
>> Signed-off-by: Baokun Li <libaokun1@huawei.com>
>> ---
>> fs/ext4/super.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
>> index 9a66abcca1a8..0ce4565422f6 100644
>> --- a/fs/ext4/super.c
>> +++ b/fs/ext4/super.c
>> @@ -6653,7 +6653,7 @@ static int ext4_write_info(struct super_block *sb, int type)
>> handle_t *handle;
>>
>> /* Data block + inode block */
>> - handle = ext4_journal_start(d_inode(sb->s_root), EXT4_HT_QUOTA, 2);
>> + handle = ext4_journal_start_sb(sb, EXT4_HT_QUOTA, 2);
>> if (IS_ERR(handle))
>> return PTR_ERR(handle);
>> ret = dquot_commit_info(sb, type);
>> --
>> 2.31.1
>>
> .
Thanks!
--
With Best Regards,
Baokun Li
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] ext4: fix null-ptr-deref in ext4_write_info
2022-08-10 7:20 ` Baokun Li
@ 2022-08-15 15:34 ` Jan Kara
0 siblings, 0 replies; 5+ messages in thread
From: Jan Kara @ 2022-08-15 15:34 UTC (permalink / raw)
To: Baokun Li
Cc: Lukas Czerner, linux-ext4, tytso, adilger.kernel, jack,
ritesh.list, enwlinux, linux-kernel, yi.zhang, yebin10, yukuai3
On Wed 10-08-22 15:20:48, Baokun Li wrote:
> 在 2022/8/5 21:07, Lukas Czerner 写道:
> > On Fri, Aug 05, 2022 at 08:39:47PM +0800, Baokun Li wrote:
> > > I caught a null-ptr-deref bug as follows:
> > > ==================================================================
> > > KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
> > > CPU: 1 PID: 1589 Comm: umount Not tainted 5.10.0-02219-dirty #339
> > > RIP: 0010:ext4_write_info+0x53/0x1b0
> > > [...]
> > > Call Trace:
> > > dquot_writeback_dquots+0x341/0x9a0
> > > ext4_sync_fs+0x19e/0x800
> > > __sync_filesystem+0x83/0x100
> > > sync_filesystem+0x89/0xf0
> > > generic_shutdown_super+0x79/0x3e0
> > > kill_block_super+0xa1/0x110
> > > deactivate_locked_super+0xac/0x130
> > > deactivate_super+0xb6/0xd0
> > > cleanup_mnt+0x289/0x400
> > > __cleanup_mnt+0x16/0x20
> > > task_work_run+0x11c/0x1c0
> > > exit_to_user_mode_prepare+0x203/0x210
> > > syscall_exit_to_user_mode+0x5b/0x3a0
> > > do_syscall_64+0x59/0x70
> > > entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > > ==================================================================
> > >
> > > Above issue may happen as follows:
> > > -------------------------------------
> > > exit_to_user_mode_prepare
> > > task_work_run
> > > __cleanup_mnt
> > > cleanup_mnt
> > > deactivate_super
> > > deactivate_locked_super
> > > kill_block_super
> > > generic_shutdown_super
> > > shrink_dcache_for_umount
> > > dentry = sb->s_root
> > > sb->s_root = NULL <--- Here set NULL
> > > sync_filesystem
> > > __sync_filesystem
> > > sb->s_op->sync_fs > ext4_sync_fs
> > > dquot_writeback_dquots
> > > sb->dq_op->write_info > ext4_write_info
> > > ext4_journal_start(d_inode(sb->s_root), EXT4_HT_QUOTA, 2)
> > > d_inode(sb->s_root)
> > > s_root->d_inode <--- Null pointer dereference
> > >
> > > To solve this problem, we use ext4_journal_start_sb directly
> > > to avoid s_root being used.
> > Are we syncing the file system after the superblock shutdown and getting
> > away with it? This does not look good. Do you have a reproducer?
> >
> > Thanks!
> > -Lukas
>
> Hi, Lukas!
>
> This problem is triggered by a pressure test when I reproduce another
> problem.
>
> So I didn't have the reproducer.
>
> I looked at the error stack code and found that it seems there is something
> wrong.
>
> Moreover, it's really weird to write code like
> "ext4_journal_start(d_inode(sb->s_root), ...)".
I agree. That looks like some leftover from the past. Feel free to add:
Reviewed-by: Jan Kara <jack@suse.cz>
Honza
>
> > > Signed-off-by: Baokun Li <libaokun1@huawei.com>
> > > ---
> > > fs/ext4/super.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> > > index 9a66abcca1a8..0ce4565422f6 100644
> > > --- a/fs/ext4/super.c
> > > +++ b/fs/ext4/super.c
> > > @@ -6653,7 +6653,7 @@ static int ext4_write_info(struct super_block *sb, int type)
> > > handle_t *handle;
> > > /* Data block + inode block */
> > > - handle = ext4_journal_start(d_inode(sb->s_root), EXT4_HT_QUOTA, 2);
> > > + handle = ext4_journal_start_sb(sb, EXT4_HT_QUOTA, 2);
> > > if (IS_ERR(handle))
> > > return PTR_ERR(handle);
> > > ret = dquot_commit_info(sb, type);
> > > --
> > > 2.31.1
> > >
> > .
>
>
> Thanks!
>
> --
> With Best Regards,
> Baokun Li
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] ext4: fix null-ptr-deref in ext4_write_info
2022-08-05 12:39 [PATCH] ext4: fix null-ptr-deref in ext4_write_info Baokun Li
2022-08-05 13:07 ` Lukas Czerner
@ 2022-09-27 21:53 ` Theodore Ts'o
1 sibling, 0 replies; 5+ messages in thread
From: Theodore Ts'o @ 2022-09-27 21:53 UTC (permalink / raw)
To: libaokun1, linux-ext4
Cc: Theodore Ts'o, lczerner, yebin10, ritesh.list, yi.zhang,
jack, linux-kernel, yukuai3, adilger.kernel, enwlinux
On Fri, 5 Aug 2022 20:39:47 +0800, Baokun Li wrote:
> I caught a null-ptr-deref bug as follows:
> ==================================================================
> KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
> CPU: 1 PID: 1589 Comm: umount Not tainted 5.10.0-02219-dirty #339
> RIP: 0010:ext4_write_info+0x53/0x1b0
> [...]
> Call Trace:
> dquot_writeback_dquots+0x341/0x9a0
> ext4_sync_fs+0x19e/0x800
> __sync_filesystem+0x83/0x100
> sync_filesystem+0x89/0xf0
> generic_shutdown_super+0x79/0x3e0
> kill_block_super+0xa1/0x110
> deactivate_locked_super+0xac/0x130
> deactivate_super+0xb6/0xd0
> cleanup_mnt+0x289/0x400
> __cleanup_mnt+0x16/0x20
> task_work_run+0x11c/0x1c0
> exit_to_user_mode_prepare+0x203/0x210
> syscall_exit_to_user_mode+0x5b/0x3a0
> do_syscall_64+0x59/0x70
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> ==================================================================
>
> [...]
Applied, thanks!
[1/1] ext4: fix null-ptr-deref in ext4_write_info
commit: 647642bf8f326994d7eaf785bba3fa9dad92cff0
Best regards,
--
Theodore Ts'o <tytso@mit.edu>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-09-27 21:54 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2022-08-05 12:39 [PATCH] ext4: fix null-ptr-deref in ext4_write_info Baokun Li
2022-08-05 13:07 ` Lukas Czerner
2022-08-10 7:20 ` Baokun Li
2022-08-15 15:34 ` Jan Kara
2022-09-27 21:53 ` Theodore Ts'o
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