* [PATCH net] ipv4: provide stronger user input validation in nl_fib_input()
@ 2017-03-22 2:22 Eric Dumazet
2017-03-22 21:18 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Eric Dumazet @ 2017-03-22 2:22 UTC (permalink / raw)
To: David Miller; +Cc: netdev, Alexander Potapenko
From: Eric Dumazet <edumazet@google.com>
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: Alexander Potapenko <glider@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
net/ipv4/fib_frontend.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 42bfd08109dd78ab509493e8d2205d72845bb3eb..8f2133ffc2ff1b94871408a5f934cb938d3462b5 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1083,7 +1083,8 @@ 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;
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net] ipv4: provide stronger user input validation in nl_fib_input()
2017-03-22 2:22 [PATCH net] ipv4: provide stronger user input validation in nl_fib_input() Eric Dumazet
@ 2017-03-22 21:18 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2017-03-22 21:18 UTC (permalink / raw)
To: eric.dumazet; +Cc: netdev, glider
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 21 Mar 2017 19:22:28 -0700
> From: Eric Dumazet <edumazet@google.com>
>
> 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: Alexander Potapenko <glider@google.com>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
Applied and queued up for -stable, thanks Eric.
^ permalink raw reply [flat|nested] 2+ messages in thread
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