diff options
| author | Mohammed Anees <pvmohammedanees2003@gmail.com> | 2024-09-24 09:32:57 +0000 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-09-26 14:01:44 -0700 |
| commit | 7bf1823e010e8db2fb649c790bd1b449a75f52d8 (patch) | |
| tree | e32508ae6645dd9e9824403682e4531d51ffce79 | |
| parent | 5ca60b86f57a4d9648f68418a725b3a7de2816b0 (diff) | |
| download | lwn-7bf1823e010e8db2fb649c790bd1b449a75f52d8.tar.gz lwn-7bf1823e010e8db2fb649c790bd1b449a75f52d8.zip | |
ocfs2: fix deadlock in ocfs2_get_system_file_inode
syzbot has found a possible deadlock in ocfs2_get_system_file_inode [1].
The scenario is depicted here,
CPU0 CPU1
lock(&ocfs2_file_ip_alloc_sem_key);
lock(&osb->system_file_mutex);
lock(&ocfs2_file_ip_alloc_sem_key);
lock(&osb->system_file_mutex);
The function calls which could lead to this are:
CPU0
ocfs2_mknod - lock(&ocfs2_file_ip_alloc_sem_key);
.
.
.
ocfs2_get_system_file_inode - lock(&osb->system_file_mutex);
CPU1 -
ocfs2_fill_super - lock(&osb->system_file_mutex);
.
.
.
ocfs2_read_virt_blocks - lock(&ocfs2_file_ip_alloc_sem_key);
This issue can be resolved by making the down_read -> down_read_try
in the ocfs2_read_virt_blocks.
[1] https://syzkaller.appspot.com/bug?extid=e0055ea09f1f5e6fabdd
Link: https://lkml.kernel.org/r/20240924093257.7181-1-pvmohammedanees2003@gmail.com
Signed-off-by: Mohammed Anees <pvmohammedanees2003@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reported-by: <syzbot+e0055ea09f1f5e6fabdd@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=e0055ea09f1f5e6fabdd
Tested-by: syzbot+e0055ea09f1f5e6fabdd@syzkaller.appspotmail.com
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | fs/ocfs2/extent_map.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c index 70a768b623cf..f7672472fa82 100644 --- a/fs/ocfs2/extent_map.c +++ b/fs/ocfs2/extent_map.c @@ -973,7 +973,13 @@ int ocfs2_read_virt_blocks(struct inode *inode, u64 v_block, int nr, } while (done < nr) { - down_read(&OCFS2_I(inode)->ip_alloc_sem); + if (!down_read_trylock(&OCFS2_I(inode)->ip_alloc_sem)) { + rc = -EAGAIN; + mlog(ML_ERROR, + "Inode #%llu ip_alloc_sem is temporarily unavailable\n", + (unsigned long long)OCFS2_I(inode)->ip_blkno); + break; + } rc = ocfs2_extent_map_get_blocks(inode, v_block + done, &p_block, &p_count, NULL); up_read(&OCFS2_I(inode)->ip_alloc_sem); |