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| author | Jeff Layton <jlayton@primarydata.com> | 2014-08-22 10:18:44 -0400 |
|---|---|---|
| committer | Jeff Layton <jlayton@primarydata.com> | 2014-10-07 14:06:12 -0400 |
| commit | bfe8602436c803c6d5e271d52cd985d491a7470a (patch) | |
| tree | 17b28bd50fd22ae65f90e9bd09cc5b14415a0049 /fs/locks.c | |
| parent | e0b93eddfe17dcb7d644eb5d6ad02a86fc41a977 (diff) | |
| download | linux-bfe8602436c803c6d5e271d52cd985d491a7470a.tar.gz linux-bfe8602436c803c6d5e271d52cd985d491a7470a.tar.bz2 linux-bfe8602436c803c6d5e271d52cd985d491a7470a.zip | |
locks: close potential race in lease_get_mtime
lease_get_mtime is called without the i_lock held, so there's no
guarantee about the stability of the list. Between the time when we
assign "flock" and then dereference it to check whether it's a lease
and for write, the lease could be freed.
Ensure that that doesn't occur by taking the i_lock before trying
to check the lease.
Cc: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs/locks.c')
| -rw-r--r-- | fs/locks.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/fs/locks.c b/fs/locks.c index f5f648e003dd..def1ac2e87bd 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -1456,8 +1456,18 @@ EXPORT_SYMBOL(__break_lease); */ void lease_get_mtime(struct inode *inode, struct timespec *time) { - struct file_lock *flock = inode->i_flock; - if (flock && IS_LEASE(flock) && (flock->fl_type == F_WRLCK)) + bool has_lease = false; + struct file_lock *flock; + + if (inode->i_flock) { + spin_lock(&inode->i_lock); + flock = inode->i_flock; + if (flock && IS_LEASE(flock) && (flock->fl_type == F_WRLCK)) + has_lease = true; + spin_unlock(&inode->i_lock); + } + + if (has_lease) *time = current_fs_time(inode->i_sb); else *time = inode->i_mtime; |