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Subject[PATCHv3] locks: prevent side-effects of locks_release_private before file_lock is initialized
Date
When calling fcntl(fd, F_SETLEASE, lck) [with lck=F_WRLCK or F_RDLCK],
the custom signal or owner (if any were previously set using F_SETSIG
or F_SETOWN fcntls) would be reset when F_SETLEASE was called for the
second time on the same file descriptor.

This bug is a regression of 2.6.37 and is described here:
https://bugzilla.kernel.org/show_bug.cgi?id=43336

This patch reverts a commit from Oct 2004 (with subject "nfs4 lease:
move the f_delown processing") which originally introduced the
lm_release_private callback.

Signed-off-by: Filipe Brandenburger <filbranden@gmail.com>
---
fs/locks.c | 17 ++++++-----------
1 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index 82c3533..6595882 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -427,18 +427,8 @@ static void lease_break_callback(struct file_lock *fl)
kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
}

-static void lease_release_private_callback(struct file_lock *fl)
-{
- if (!fl->fl_file)
- return;
-
- f_delown(fl->fl_file);
- fl->fl_file->f_owner.signum = 0;
-}
-
static const struct lock_manager_operations lease_manager_ops = {
.lm_break = lease_break_callback,
- .lm_release_private = lease_release_private_callback,
.lm_change = lease_modify,
};

@@ -1155,8 +1145,13 @@ int lease_modify(struct file_lock **before, int arg)
return error;
lease_clear_pending(fl, arg);
locks_wake_up_blocks(fl);
- if (arg == F_UNLCK)
+ if (arg == F_UNLCK) {
+ struct file *filp = fl->fl_file;
+
+ f_delown(filp);
+ filp->f_owner.signum = 0;
locks_delete_lock(before);
+ }
return 0;
}

--
1.7.7.6


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