From: Eric Dumazet edumazet@google.com
This patch has been added to the stable tree. If you have any objections, please let us know.
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[ 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: Alexander Potapenko glider@google.com Signed-off-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@microsoft.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 765909ba781e..a8db70b7fe45 100644 --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -1033,7 +1033,8 @@ 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;