netdevsim: zero initialize struct iphdr in dummy sk_buff

Syzbot reports a KMSAN uninit-value originating from
nsim_dev_trap_skb_build, with the allocation also
being performed in the same function.

Fix this by calling skb_put_zero instead of skb_put to
guarantee zero initialization of the whole IP header.

Closes: https://syzkaller.appspot.com/bug?extid=23d7fcd204e3837866ff
Fixes: da58f90f11 ("netdevsim: Add devlink-trap support")
Signed-off-by: Nikola Z. Ivanov <zlatistiv@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260426201434.742030-1-zlatistiv@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Nikola Z. Ivanov
2026-04-26 23:14:34 +03:00
committed by Jakub Kicinski
parent 3618442d54
commit 35eaa6d8d6

View File

@@ -829,7 +829,7 @@ static struct sk_buff *nsim_dev_trap_skb_build(void)
skb->protocol = htons(ETH_P_IP);
skb_set_network_header(skb, skb->len);
iph = skb_put(skb, sizeof(struct iphdr));
iph = skb_put_zero(skb, sizeof(struct iphdr));
iph->protocol = IPPROTO_UDP;
iph->saddr = in_aton("192.0.2.1");
iph->daddr = in_aton("198.51.100.1");