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Ivanov" To: kuba@kernel.org, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Nikola Z. Ivanov" Subject: [PATCH net v2] netdevsim: zero initialize struct iphdr in dummy sk_buff Date: Sun, 26 Apr 2026 23:14:34 +0300 Message-ID: <20260426201434.742030-1-zlatistiv@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- Changes since v1: - avoid unnecessary shuffling of struct member initialization. https://lore.kernel.org/netdev/20260421082005.74a3efb4@kernel.org/ 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"); -- 2.53.0