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Commit 62e85fe5 authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
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ipv4: provide stronger user input validation in nl_fib_input() 



[ Upstream commit c64c0b3cac4c5b8cb093727d2c19743ea3965c0b ]

Alexander reported a KMSAN splat caused by reads of uninitialized
field (tb_id_in) from user provided struct fib_result_nl

It turns out nl_fib_input() sanity tests on user input is a bit
wrong :

User can pretend nlh->nlmsg_len is big enough, but provide
at sendmsg() time a too small buffer.

Reported-by: default avatarAlexander Potapenko <glider@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2f94dd54

net/ipv4/fib_frontend.c

+2 −1
Original line number Diff line number Diff line
@@ -1081,7 +1081,8 @@ static void nl_fib_input(struct sk_buff *skb) 


	net = sock_net(skb->sk);

	nlh = nlmsg_hdr(skb);

	if (skb->len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len ||

	if (skb->len < nlmsg_total_size(sizeof(*frn)) ||

	    skb->len < nlh->nlmsg_len ||

	    nlmsg_len(nlh) < sizeof(*frn))

		return;