From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f202.google.com (mail-yb1-f202.google.com [209.85.219.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EA7D131A69 for ; Fri, 5 Jan 2024 17:03:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Owghbxc3" Received: by mail-yb1-f202.google.com with SMTP id 3f1490d57ef6-dbeaf21e069so2295416276.1 for ; Fri, 05 Jan 2024 09:03:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1704474195; x=1705078995; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=BI25y7OUP0OOtbnQjwp++yy7r1tF+jkjB+PSnSVtMWI=; b=Owghbxc3Ps8oco5W3n1lJQbgRM1R8vs0SJXp6c8rjB7XjXZRSSkOyEkfOPFjpllVzL aha3gnUosyBCKkHIxH68T3BR3i+5ugLPrIh1fpUnmJMNNqpHRsaejQJq+ukcsG2PUXXZ so88LsxdaFLXDKjviQ0uPR1BrUMMflJIDA5AFSGjhkeH+P3rl7cf6WoDTlNYQpPzoQmm ki8kBiHdbQDWuWkvKqT+QEuy8drSka4em7LgwHrhVrfXZVvK7Xb8n738KRHv5mpbP8i3 ZIBbvMg7SpmIC2oQ5cZ2GCs3x2ICrXDFvP99jTqv2Cf4zg/9xjRERrDayCOABM1FgDcc 4zKQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1704474195; x=1705078995; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=BI25y7OUP0OOtbnQjwp++yy7r1tF+jkjB+PSnSVtMWI=; b=rSKpUPN0l4KGIRZso4TtQqbR/aNNND/gkBG0mPnMGF0chzCD1tRjgAGqinQkrA3ynN QUOPU9DPho90eaWw1ehdljlbn+FGgKGIDQwelrSrK1HpJ4FaGR0S6sPrEOQPk6VsO2Pc G/YopiNU1aiGV0GepevmW9i3sjCEombHMHP0rs7tBAlUXAx+R3sDVv9YfreeBbvlq6Pg i0ZJSGvJQGhr30KS6BjBIgH/RMCGmWc9d03Db5rMstMgTozQOrXlMVQt1rVsk7qpQT+3 wTJvSNrk6y23vXybhznbwXjcD0geDnGULd8u4GHN/yWHqBM406UhdVO/PlVsm1byDEQH /Gng== X-Gm-Message-State: AOJu0YzDnXAb+85OAK+LjygqSaFLHd88M5moG2E0F3tPqCjiUGqzWiLo w/2hnx3yRTO8dSCbRSgjTNo/BZmpqAVIELDR5vLF X-Google-Smtp-Source: AGHT+IE3i0N6VgXQs9LYlHuFyWZPT8YtOYml+H2nkrVaBXR7IsSKujmvNdZ8+pB+g6Qi0GHEaKnngLJZZ3BVug== X-Received: from edumazet1.c.googlers.com ([fda3:e722:ac3:cc00:2b:7d90:c0a8:395a]) (user=edumazet job=sendgmr) by 2002:a25:bfc6:0:b0:dbd:b7cb:8a6b with SMTP id q6-20020a25bfc6000000b00dbdb7cb8a6bmr82034ybm.1.1704474194795; Fri, 05 Jan 2024 09:03:14 -0800 (PST) Date: Fri, 5 Jan 2024 17:03:13 +0000 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.43.0.472.g3155946c3a-goog Message-ID: <20240105170313.2946078-1-edumazet@google.com> Subject: [PATCH net] ip6_tunnel: fix NEXTHDR_FRAGMENT handling in ip6_tnl_parse_tlv_enc_lim() From: Eric Dumazet To: "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: David Ahern , Willem de Bruijn , netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet , syzbot Content-Type: text/plain; charset="UTF-8" syzbot pointed out [1] that NEXTHDR_FRAGMENT handling is broken. Reading frag_off can only be done if we pulled enough bytes to skb->head. Currently we might access garbage. [1] BUG: KMSAN: uninit-value in ip6_tnl_parse_tlv_enc_lim+0x94f/0xbb0 ip6_tnl_parse_tlv_enc_lim+0x94f/0xbb0 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1326 [inline] ip6_tnl_start_xmit+0xab2/0x1a70 net/ipv6/ip6_tunnel.c:1432 __netdev_start_xmit include/linux/netdevice.h:4940 [inline] netdev_start_xmit include/linux/netdevice.h:4954 [inline] xmit_one net/core/dev.c:3548 [inline] dev_hard_start_xmit+0x247/0xa10 net/core/dev.c:3564 __dev_queue_xmit+0x33b8/0x5130 net/core/dev.c:4349 dev_queue_xmit include/linux/netdevice.h:3134 [inline] neigh_connected_output+0x569/0x660 net/core/neighbour.c:1592 neigh_output include/net/neighbour.h:542 [inline] ip6_finish_output2+0x23a9/0x2b30 net/ipv6/ip6_output.c:137 ip6_finish_output+0x855/0x12b0 net/ipv6/ip6_output.c:222 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip6_output+0x323/0x610 net/ipv6/ip6_output.c:243 dst_output include/net/dst.h:451 [inline] ip6_local_out+0xe9/0x140 net/ipv6/output_core.c:155 ip6_send_skb net/ipv6/ip6_output.c:1952 [inline] ip6_push_pending_frames+0x1f9/0x560 net/ipv6/ip6_output.c:1972 rawv6_push_pending_frames+0xbe8/0xdf0 net/ipv6/raw.c:582 rawv6_sendmsg+0x2b66/0x2e70 net/ipv6/raw.c:920 inet_sendmsg+0x105/0x190 net/ipv4/af_inet.c:847 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 __sys_sendmsg net/socket.c:2667 [inline] __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b Uninit was created at: slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768 slab_alloc_node mm/slub.c:3478 [inline] __kmem_cache_alloc_node+0x5c9/0x970 mm/slub.c:3517 __do_kmalloc_node mm/slab_common.c:1006 [inline] __kmalloc_node_track_caller+0x118/0x3c0 mm/slab_common.c:1027 kmalloc_reserve+0x249/0x4a0 net/core/skbuff.c:582 pskb_expand_head+0x226/0x1a00 net/core/skbuff.c:2098 __pskb_pull_tail+0x13b/0x2310 net/core/skbuff.c:2655 pskb_may_pull_reason include/linux/skbuff.h:2673 [inline] pskb_may_pull include/linux/skbuff.h:2681 [inline] ip6_tnl_parse_tlv_enc_lim+0x901/0xbb0 net/ipv6/ip6_tunnel.c:408 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1326 [inline] ip6_tnl_start_xmit+0xab2/0x1a70 net/ipv6/ip6_tunnel.c:1432 __netdev_start_xmit include/linux/netdevice.h:4940 [inline] netdev_start_xmit include/linux/netdevice.h:4954 [inline] xmit_one net/core/dev.c:3548 [inline] dev_hard_start_xmit+0x247/0xa10 net/core/dev.c:3564 __dev_queue_xmit+0x33b8/0x5130 net/core/dev.c:4349 dev_queue_xmit include/linux/netdevice.h:3134 [inline] neigh_connected_output+0x569/0x660 net/core/neighbour.c:1592 neigh_output include/net/neighbour.h:542 [inline] ip6_finish_output2+0x23a9/0x2b30 net/ipv6/ip6_output.c:137 ip6_finish_output+0x855/0x12b0 net/ipv6/ip6_output.c:222 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip6_output+0x323/0x610 net/ipv6/ip6_output.c:243 dst_output include/net/dst.h:451 [inline] ip6_local_out+0xe9/0x140 net/ipv6/output_core.c:155 ip6_send_skb net/ipv6/ip6_output.c:1952 [inline] ip6_push_pending_frames+0x1f9/0x560 net/ipv6/ip6_output.c:1972 rawv6_push_pending_frames+0xbe8/0xdf0 net/ipv6/raw.c:582 rawv6_sendmsg+0x2b66/0x2e70 net/ipv6/raw.c:920 inet_sendmsg+0x105/0x190 net/ipv4/af_inet.c:847 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 __sys_sendmsg net/socket.c:2667 [inline] __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b CPU: 0 PID: 7345 Comm: syz-executor.3 Not tainted 6.7.0-rc8-syzkaller-00024-gac865f00af29 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023 Fixes: fbfa743a9d2a ("ipv6: fix ip6_tnl_parse_tlv_enc_lim()") Reported-by: syzbot Signed-off-by: Eric Dumazet Cc: Willem de Bruijn --- net/ipv6/ip6_tunnel.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c index 5e80e517f071013410349d1fd93afc00a394e284..46c19bd4899011d53b4feb84e25013c01ddce701 100644 --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -399,7 +399,7 @@ __u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw) const struct ipv6hdr *ipv6h = (const struct ipv6hdr *)raw; unsigned int nhoff = raw - skb->data; unsigned int off = nhoff + sizeof(*ipv6h); - u8 next, nexthdr = ipv6h->nexthdr; + u8 nexthdr = ipv6h->nexthdr; while (ipv6_ext_hdr(nexthdr) && nexthdr != NEXTHDR_NONE) { struct ipv6_opt_hdr *hdr; @@ -410,25 +410,25 @@ __u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw) hdr = (struct ipv6_opt_hdr *)(skb->data + off); if (nexthdr == NEXTHDR_FRAGMENT) { - struct frag_hdr *frag_hdr = (struct frag_hdr *) hdr; - if (frag_hdr->frag_off) - break; optlen = 8; } else if (nexthdr == NEXTHDR_AUTH) { optlen = ipv6_authlen(hdr); } else { optlen = ipv6_optlen(hdr); } - /* cache hdr->nexthdr, since pskb_may_pull() might - * invalidate hdr - */ - next = hdr->nexthdr; - if (nexthdr == NEXTHDR_DEST) { - u16 i = 2; - /* Remember : hdr is no longer valid at this point. */ - if (!pskb_may_pull(skb, off + optlen)) + if (!pskb_may_pull(skb, off + optlen)) + break; + + hdr = (struct ipv6_opt_hdr *)(skb->data + off); + if (nexthdr == NEXTHDR_FRAGMENT) { + struct frag_hdr *frag_hdr = (struct frag_hdr *)hdr; + + if (frag_hdr->frag_off) break; + } + if (nexthdr == NEXTHDR_DEST) { + u16 i = 2; while (1) { struct ipv6_tlv_tnl_enc_lim *tel; @@ -449,7 +449,7 @@ __u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw) i++; } } - nexthdr = next; + nexthdr = hdr->nexthdr; off += optlen; } return 0; -- 2.43.0.472.g3155946c3a-goog