9p: clear dangling pointers in p9stat_free
[ Upstream commit 62e3941776fea8678bb8120607039410b1b61a65 ]
p9stat_free is more of a cleanup function than a 'free' function as it
only frees the content of the struct; there are chances of use-after-free
if it is improperly used (e.g. p9stat_free called twice as it used to be
possible to)
Clearing dangling pointers makes the function idempotent and safer to use.
Link: http://lkml.kernel.org/r/1535410108-20650-2-git-send-email-asmadeus@codewreck.org
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Reported-by: syzbot+d4252148d198410b864f@syzkaller.appspotmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
diff --git a/net/9p/protocol.c b/net/9p/protocol.c
index 16d2875..145f805 100644
--- a/net/9p/protocol.c
+++ b/net/9p/protocol.c
@@ -46,10 +46,15 @@
void p9stat_free(struct p9_wstat *stbuf)
{
kfree(stbuf->name);
+ stbuf->name = NULL;
kfree(stbuf->uid);
+ stbuf->uid = NULL;
kfree(stbuf->gid);
+ stbuf->gid = NULL;
kfree(stbuf->muid);
+ stbuf->muid = NULL;
kfree(stbuf->extension);
+ stbuf->extension = NULL;
}
EXPORT_SYMBOL(p9stat_free);
