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

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>

diff --git a/net/9p/client.c b/net/9p/client.c
index 8bc8b3e91532df66762a339ab30ba1407760fa92..dd461c718cf992b9382af1094736fc4c6f0bae29 100644 (file)
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -958,7 +958,7 @@ 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",