diff options
| author | Baokun Li | 2022-08-05 20:39:47 +0800 |
|---|---|---|
| committer | Theodore Ts'o | 2022-09-29 10:39:04 -0400 |
| commit | f9c1f248607d5546075d3f731e7607d5571f2b60 (patch) | |
| tree | 2ba14bc310208bf3d3ab57c6bfe8bac7e3cdcdbb | |
| parent | 426d15ad11419066f7042ffa8fbf1b5c21a1ecbe (diff) | |
ext4: fix null-ptr-deref in ext4_write_info
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.
Cc: stable@kernel.org
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220805123947.565152-1-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | fs/ext4/super.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index afbbf07f58a7..aba4b1fca9e4 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -6644,7 +6644,7 @@ 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); |