net/wan: fix a double free in x25_asy_open_tty()

congwang · davem330 · commit d5c7c745f254 · 2018-12-30T20:22:48.000-08:00
When x25_asy_open() fails, it already cleans up by itself, so its caller doesn't need to free the memory again. It seems we still have to call x25_asy_free() to clear the SLF_INUSE bit, so just set these pointers to NULL after kfree(). Reported-and-tested-by: syzbot+5e5e969e525129229052@syzkaller.appspotmail.com Fixes: 3b780be ("x25_asy: Free x25_asy on x25_asy_open() failure.") Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/wan/x25_asy.c b/drivers/net/wan/x25_asy.c
@@ -485,8 +485,10 @@ static int x25_asy_open(struct net_device *dev)
 
 	/* Cleanup */
 	kfree(sl->xbuff);
+	sl->xbuff = NULL;
 noxbuff:
 	kfree(sl->rbuff);
+	sl->rbuff = NULL;
 norbuff:
 	return -ENOMEM;
 }
