From fef0035c0f31322d417d1954bba5ab959bf91183 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Thu, 28 Sep 2017 00:41:44 +0200 Subject: [PATCH] netlink: do not proceed if dump's start() errs Drivers that use the start method for netlink dumping rely on dumpit not being called if start fails. For example, ila_xlat.c allocates memory and assigns it to cb->args[0] in its start() function. It might fail to do that and return -ENOMEM instead. However, even when returning an error, dumpit will be called, which, in the example above, quickly dereferences the memory in cb->args[0], which will OOPS the kernel. This is but one example of how this goes wrong. Since start() has always been a function with an int return type, it therefore makes sense to use it properly, rather than ignoring it. This patch thus returns early and does not call dumpit() when start() fails. Signed-off-by: Jason A. Donenfeld Cc: Johannes Berg Reviewed-by: Johannes Berg Signed-off-by: David S. Miller --- net/netlink/af_netlink.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 327807731b44..94c11cf0459d 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2270,10 +2270,13 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, mutex_unlock(nlk->cb_mutex); + ret = 0; if (cb->start) - cb->start(cb); + ret = cb->start(cb); + + if (!ret) + ret = netlink_dump(sk); - ret = netlink_dump(sk); sock_put(sk); if (ret)