From 35eaa6d8d6c2ee65e96f507add856e0eacf24591 Mon Sep 17 00:00:00 2001 From: "Nikola Z. Ivanov" Date: Sun, 26 Apr 2026 23:14:34 +0300 Subject: 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: da58f90f11f5 ("netdevsim: Add devlink-trap support") Signed-off-by: Nikola Z. Ivanov Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260426201434.742030-1-zlatistiv@gmail.com Signed-off-by: Jakub Kicinski --- drivers/net/netdevsim/dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c index 1e06e781c835..f00fc2f9ebde 100644 --- a/drivers/net/netdevsim/dev.c +++ b/drivers/net/netdevsim/dev.c @@ -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"); -- cgit v1.2.3