cluster: RHEL48 - Bug in GFS locking code leads to dos

[Bob Peterson]

Gitweb:       
http://git.fedorahosted.org/git/cluster.git?p=cluster.git;a=commitdiff;h=...
Commit:        19bb0c8920a245c58f1a96d8e37387f7d83d1f17
Parent:        35f94eace1e0b3b1c4b9da50d26ba8a1fdbf0716
Author:        Bob Peterson <rpeterso(a)redhat.com&gt;
AuthorDate:    Thu Mar 11 11:35:01 2010 -0600
Committer:     Bob Peterson <rpeterso(a)redhat.com&gt;
CommitterDate: Thu Mar 11 11:43:51 2010 -0600

Bug in GFS locking code leads to dos

This patch fixes the bug described in bug 570863.
Without the patch, a program may be written that uses
locking commands to crash the system.

rhbz#571299
---
 gfs-kernel/src/gfs/ops_file.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/gfs-kernel/src/gfs/ops_file.c b/gfs-kernel/src/gfs/ops_file.c
index 4d263ee..46cfec2 100644
--- a/gfs-kernel/src/gfs/ops_file.c
+++ b/gfs-kernel/src/gfs/ops_file.c
@@ -1625,7 +1625,8 @@ gfs_lock(struct file *file, int cmd, struct file_lock *fl)
 
 	if (!(fl->fl_flags & FL_POSIX))
 		return -ENOLCK;
-	if ((ip->i_di.di_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
+	if ((ip->i_di.di_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
+	    fl->fl_type != F_UNLCK)
 		return -ENOLCK;
 
 	if (sdp->sd_args.ar_localflocks) {