Commit 102f190c authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman

ipv4: provide stronger user input validation in nl_fib_input()

commit c64c0b3c upstream.

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 3f01e667
...@@ -961,7 +961,8 @@ static void nl_fib_input(struct sk_buff *skb) ...@@ -961,7 +961,8 @@ static void nl_fib_input(struct sk_buff *skb)
net = sock_net(skb->sk); net = sock_net(skb->sk);
nlh = nlmsg_hdr(skb); 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)) nlmsg_len(nlh) < sizeof(*frn))
return; return;
......
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