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 <[email protected]> Signed-off-by: Jeff Layton <[email protected]> --- fs/locks.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/fs/locks.c b/fs/locks.c index d7e15a256f8f..58ce8897f2e4 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; -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
