net/9p/client.c: version pointer uninitialized

commit 7913690dcc5e18e235769fd87c34143072f5dbea upstream.

The p9_client_version() does not initialize the version pointer. If the
call to p9pdu_readf() returns an error and version has not been allocated
in p9pdu_readf(), then the program will jump to the "error" label and will
try to free the version pointer. If version is not initialized, free()
will be called with uninitialized, garbage data and will provoke a crash.

Link: http://lkml.kernel.org/r/20180709222943.19503-1-tomasbortoli@gmail.com
Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
Reported-by: syzbot+65c6b72f284a39d416b4@syzkaller.appspotmail.com
Reviewed-by: Jun Piao <piaojun@huawei.com>
Reviewed-by: Yiwen Jiang <jiangyiwen@huawei.com>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/9p/client.c b/net/9p/client.c
index b433aff5ff13ce9e10cddc204f97f9f19ae6c979..3ec5a82929b23d10aa3ccad572021aa2797984b2 100644 (file)
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -955,7 +955,7 @@ static int p9_client_version(struct p9_client *c)
 {
        int err = 0;
        struct p9_req_t *req;
-       char *version;
+       char *version = NULL;
        int msize;
 
        p9_debug(P9_DEBUG_9P, ">>> TVERSION msize %d protocol %d\n",