From: Vasily Averin <vvs@virtuozzo.com>
Date: Thu, 14 Jan 2016 10:41:14 +0000 (+0300)
Subject: cifs_dbg() outputs an uninitialized buffer in cifs_readdir()
X-Git-Tag: v4.1.12-92~150^2~298
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=927d6d5ab153eb9f72a2d82c7f497d52532a87d4;p=users%2Fjedix%2Flinux-maple.git

cifs_dbg() outputs an uninitialized buffer in cifs_readdir()

Orabug: 23330633

[ Upstream commit 01b9b0b28626db4a47d7f48744d70abca9914ef1 ]

In some cases tmp_bug can be not filled in cifs_filldir and stay uninitialized,
therefore its printk with "%s" modifier can leak content of kernelspace memory.
If old content of this buffer does not contain '\0' access bejond end of
allocated object can crash the host.

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Steve French <sfrench@localhost.localdomain>
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit c5882812d2e1ab7db5bc71a1bca90b3a2d89dedd)

Signed-off-by: Dan Duval <dan.duval@oracle.com>
---

diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index b1eede3678a91..3634c7adf7d20 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -847,6 +847,7 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 		 * if buggy server returns . and .. late do we want to
 		 * check for that here?
 		 */
+		*tmp_buf = 0;
 		rc = cifs_filldir(current_entry, file, ctx,
 				  tmp_buf, max_len);
 		if (rc) {