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Commit ec3e32de authored by Mohammed Anees's avatar Mohammed Anees Committed by Greg Kroah-Hartman
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ocfs2: fix deadlock in ocfs2_get_system_file_inode

commit 7bf1823e010e8db2fb649c790bd1b449a75f52d8 upstream.

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: default avatarMohammed Anees <pvmohammedanees2003@gmail.com>
Reviewed-by: default avatarJoseph Qi <joseph.qi@linux.alibaba.com>
Reported-by: default avatar <syzbot+e0055ea09f1f5e6fabdd@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=e0055ea09f1f5e6fabdd


Tested-by: default avatar <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: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Xingyu Li <xli399@ucr.edu>
Cc: Zheng Zhang <zzhan173@ucr.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1364a29b
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