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From: Jia-Ju Bai <baijiaju1990@163.com>
To: viro@zeniv.linux.org.uk, dhowells@redhat.com
Cc: linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [BUG] fs/afs/flock: possible sleep-in-atomic bugs in afs_do_setlk
Date: Sat, 7 Oct 2017 18:11:01 +0800	[thread overview]
Message-ID: <8aff89e4-e880-7e97-8b29-37822f4d2e02@163.com> (raw)

According to fs/afs/flock.c, the kernel may sleep under a spinlock,
and the function call paths are:
afs_do_setlk (acquire the spinlock: inode->i_lock)
   afs_vnode_fetch_status
     schedule --> may sleep

afs_do_setlk (acquire the spinlock: inode->i_lock)
   wait_event_interruptible --> may sleep

These bugs may be introduced by only considering "vnode->lock" but 
ignoring "inode->i_lock".

A possible fix is to unlock "inode->i_lock" before calling 
afs_vnode_fetch_status and wait_event_interruptible, and lock 
"inode->i_lock" again after them.

These bugs are found by my static analysis tool and my code review.


Thanks,
Jia-Ju Bai

                 reply	other threads:[~2017-10-07 10:11 UTC|newest]

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