From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 68FA23D300D; Thu, 15 Jan 2026 17:56:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768499783; cv=none; b=sKxhwkQlI5Bi1D3ORq/9Zbp9r3WSpxa0OZr7bLggAMtUkPY2Ds3YvWKqGkzkYphoub7t2Br1PAa944JbcZug+5iQaIA31VQr8ToR9bpwvk0yn9T1ppBTNj2hE8ELRsxq107vGDgA3biYjlvPP0GXfRfMacmkdUCYKHEZeFIDnT0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768499783; c=relaxed/simple; bh=Qg6jNMUWudkFm2QfVEG+gpAcfCU8zf82j4pjPGlk38Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uRcs9V+8uSMjX3ve44CUzQ3TLSHTbX9VjQRDphJTwTHRlQ+B9uO1WlxMCuqyK6+6yPxdGpUomPacynMXosQiBSAvboo2hnbcSlJmjRVExA8w/LMaer3oUQCCgtihtzYe/KkS1dVbthZvyNAGjQAuNZvSC6227izkRRHVswL7KuM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=sMzGtDLO; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="sMzGtDLO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DC75BC116D0; Thu, 15 Jan 2026 17:56:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1768499783; bh=Qg6jNMUWudkFm2QfVEG+gpAcfCU8zf82j4pjPGlk38Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sMzGtDLOMrP352bmjbS/cSlZOuXjvtNSAqoufWnqIjxV/bWg4sBve+6Nt33gvvdha CDX8Z/DmRa7jxSbPtST9pURNyyGzyj6W/11zih+HRcCFw+w9WFVKWmOqyfi+B8Mjhr ddjmsA4pvcxDV7AM3YskKrxkFpe7IaweNDXgRtQs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzkaller , Shigeru Yoshida , Paolo Abeni , Shubham Kulkarni Subject: [PATCH 5.10 349/451] ipv4: Fix uninit-value access in __ip_make_skb() Date: Thu, 15 Jan 2026 17:49:10 +0100 Message-ID: <20260115164243.525160971@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260115164230.864985076@linuxfoundation.org> References: <20260115164230.864985076@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Shigeru Yoshida commit fc1092f51567277509563800a3c56732070b6aa4 upstream. KMSAN reported uninit-value access in __ip_make_skb() [1]. __ip_make_skb() tests HDRINCL to know if the skb has icmphdr. However, HDRINCL can cause a race condition. If calling setsockopt(2) with IP_HDRINCL changes HDRINCL while __ip_make_skb() is running, the function will access icmphdr in the skb even if it is not included. This causes the issue reported by KMSAN. Check FLOWI_FLAG_KNOWN_NH on fl4->flowi4_flags instead of testing HDRINCL on the socket. Also, fl4->fl4_icmp_type and fl4->fl4_icmp_code are not initialized. These are union in struct flowi4 and are implicitly initialized by flowi4_init_output(), but we should not rely on specific union layout. Initialize these explicitly in raw_sendmsg(). [1] BUG: KMSAN: uninit-value in __ip_make_skb+0x2b74/0x2d20 net/ipv4/ip_output.c:1481 __ip_make_skb+0x2b74/0x2d20 net/ipv4/ip_output.c:1481 ip_finish_skb include/net/ip.h:243 [inline] ip_push_pending_frames+0x4c/0x5c0 net/ipv4/ip_output.c:1508 raw_sendmsg+0x2381/0x2690 net/ipv4/raw.c:654 inet_sendmsg+0x27b/0x2a0 net/ipv4/af_inet.c:851 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x274/0x3c0 net/socket.c:745 __sys_sendto+0x62c/0x7b0 net/socket.c:2191 __do_sys_sendto net/socket.c:2203 [inline] __se_sys_sendto net/socket.c:2199 [inline] __x64_sys_sendto+0x130/0x200 net/socket.c:2199 do_syscall_64+0xd8/0x1f0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x6d/0x75 Uninit was created at: slab_post_alloc_hook mm/slub.c:3804 [inline] slab_alloc_node mm/slub.c:3845 [inline] kmem_cache_alloc_node+0x5f6/0xc50 mm/slub.c:3888 kmalloc_reserve+0x13c/0x4a0 net/core/skbuff.c:577 __alloc_skb+0x35a/0x7c0 net/core/skbuff.c:668 alloc_skb include/linux/skbuff.h:1318 [inline] __ip_append_data+0x49ab/0x68c0 net/ipv4/ip_output.c:1128 ip_append_data+0x1e7/0x260 net/ipv4/ip_output.c:1365 raw_sendmsg+0x22b1/0x2690 net/ipv4/raw.c:648 inet_sendmsg+0x27b/0x2a0 net/ipv4/af_inet.c:851 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x274/0x3c0 net/socket.c:745 __sys_sendto+0x62c/0x7b0 net/socket.c:2191 __do_sys_sendto net/socket.c:2203 [inline] __se_sys_sendto net/socket.c:2199 [inline] __x64_sys_sendto+0x130/0x200 net/socket.c:2199 do_syscall_64+0xd8/0x1f0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x6d/0x75 CPU: 1 PID: 15709 Comm: syz-executor.7 Not tainted 6.8.0-11567-gb3603fcb79b1 #25 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-1.fc39 04/01/2014 Fixes: 99e5acae193e ("ipv4: Fix potential uninit variable access bug in __ip_make_skb()") Reported-by: syzkaller Signed-off-by: Shigeru Yoshida Link: https://lore.kernel.org/r/20240430123945.2057348-1-syoshida@redhat.com Signed-off-by: Paolo Abeni [ Referred stable v6.1.y version of the patch to generate this one v6.1 link: https://github.com/gregkh/linux/commit/55bf541e018b76b3750cb6c6ea18c46e1ac5562e ] Signed-off-by: Shubham Kulkarni Signed-off-by: Greg Kroah-Hartman --- net/ipv4/ip_output.c | 3 ++- net/ipv4/raw.c | 3 +++ 2 files changed, 5 insertions(+), 1 deletion(-) --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -1572,7 +1572,8 @@ struct sk_buff *__ip_make_skb(struct soc * so icmphdr does not in skb linear region and can not get icmp_type * by icmp_hdr(skb)->type. */ - if (sk->sk_type == SOCK_RAW && !inet_sk(sk)->hdrincl) + if (sk->sk_type == SOCK_RAW && + !(fl4->flowi4_flags & FLOWI_FLAG_KNOWN_NH)) icmp_type = fl4->fl4_icmp_type; else icmp_type = icmp_hdr(skb)->type; --- a/net/ipv4/raw.c +++ b/net/ipv4/raw.c @@ -634,6 +634,9 @@ static int raw_sendmsg(struct sock *sk, (hdrincl ? FLOWI_FLAG_KNOWN_NH : 0), daddr, saddr, 0, 0, sk->sk_uid); + fl4.fl4_icmp_type = 0; + fl4.fl4_icmp_code = 0; + if (!hdrincl) { rfv.msg = msg; rfv.hlen = 0;