From: Sage Weil <sage@newdream.net>
Date: Tue, 23 Nov 2010 06:58:06 +0000 (-0800)
Subject: ceph: avoid possible null deref in readdir after dir llseek
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=884ea892763d4dfba509743f65961c782c0442db;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git

ceph: avoid possible null deref in readdir after dir llseek

last may be NULL, but we dereference it in the else branch without
checking.  Normally it doesn't trigger because last == NULL when fpos == 2,
but it could happen on a newly opened dir if the user seeks forward.

Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Sage Weil <sage@newdream.net>
---

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 7d447af84ec4..158c700fdca5 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -114,8 +114,8 @@ static int __dcache_readdir(struct file *filp,
 	spin_lock(&dcache_lock);
 
 	/* start at beginning? */
-	if (filp->f_pos == 2 || (last &&
-				 filp->f_pos < ceph_dentry(last)->offset)) {
+	if (filp->f_pos == 2 || last == NULL ||
+	    filp->f_pos < ceph_dentry(last)->offset) {
 		if (list_empty(&parent->d_subdirs))
 			goto out_unlock;
 		p = parent->d_subdirs.prev;