cifs_dbg() outputs an uninitialized buffer in cifs_readdir()

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>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index 0557c45e9c33..b30a4a6d98a0 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) {