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: v3.14.62~31
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=827f86f6a3b2f37d4757a4f49b02bfb2c1580602;p=thirdparty%2Fkernel%2Fstable.git

cifs_dbg() outputs an uninitialized buffer in cifs_readdir()

commit 01b9b0b28626db4a47d7f48744d70abca9914ef1 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index b334a89d6a66e..1320d1ecc6309 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -849,6 +849,7 @@ 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) {