From nobody Mon Feb 9 14:34:57 2026 Received: from new-mail.astralinux.ru (new-mail.astralinux.ru [51.250.53.244]) (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 3C265D51E; Tue, 6 Feb 2024 17:39:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=51.250.53.244 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707241180; cv=none; b=iegEd2WtIUEZkWwyLYCD1GUssueKkF+Xf68/n3Fk5NV2rWAXYDbtl7ICXB2kucsq7Ui7Gf/4+OT8/jGpS32uoxrYAe0Ngchc6laTjDJ6ztr+LepwV2w4DEzrqIMwUh7IxSCIeH5WyOoc3OPPxmAouVbHoMWvDeCqlOAIq8EvqJg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707241180; c=relaxed/simple; bh=WWwZvRC7leIgoRx3cVsCE5ZZDk1l0qoJfM+AQd5L5IE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=QHiFaKClovMxUBlsV61hoAY3YWkCx8OGZQO0Ne56JaVWPAmB1uDeX4oJZR0f+JHM7cVNiI+8u1n7doUI+vPAivx3/khqNyZlaIOaKXLWn+KUgOkGOl4S2qpEHiNbmhEB7qvttH4eoTQ3E4cdQVgxSZDJMV4RKroQQnY3ibvj80w= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=astralinux.ru; spf=pass smtp.mailfrom=astralinux.ru; arc=none smtp.client-ip=51.250.53.244 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=astralinux.ru Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=astralinux.ru Received: from rbta-msk-lt-156703.astralinux.ru (unknown [10.177.20.15]) by new-mail.astralinux.ru (Postfix) with ESMTPA id 4TTr915VGbzfYwR; Tue, 6 Feb 2024 20:39:33 +0300 (MSK) From: Alexey Panov To: stable@vger.kernel.org, Greg Kroah-Hartman Cc: Alexey Panov , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Sasha Levin , Kuniyuki Iwashima , Mohamed Khalfella , Pratyush Yadav , Kees Cook , Liang Chen , Marcelo Ricardo Leitner , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, lvc-project@linuxtesting.org, Willem de Bruijn Subject: [PATCH 5.10/5.15/6.1 1/1] net: prevent mss overflow in skb_segment() Date: Tue, 6 Feb 2024 20:38:44 +0300 Message-Id: <20240206173844.30271-2-apanov@astralinux.ru> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20240206173844.30271-1-apanov@astralinux.ru> References: <20240206173844.30271-1-apanov@astralinux.ru> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-DrWeb-SpamScore: -100 X-DrWeb-SpamState: legit X-DrWeb-SpamDetail: gggruggvucftvghtrhhoucdtuddrgedvfedrvdehuddgtddvucetufdoteggodetrfcurfhrohhfihhlvgemucfftfghgfeunecuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhvfevufffkffojghfggfgsedtkeertdertddtnecuhfhrohhmpeetlhgvgigvhicurfgrnhhovhcuoegrphgrnhhovhesrghsthhrrghlihhnuhigrdhruheqnecuggftrfgrthhtvghrnhepteeigfefledvueefgfdvieejgefgieeiiefggeekueejheefvdekvdefhfduudetnecuffhomhgrihhnpehkvghrnhgvlhdrohhrghenucfkphepuddtrddujeejrddvtddrudehnecurfgrrhgrmhephhgvlhhopehrsghtrgdqmhhskhdqlhhtqdduheeijedtfedrrghsthhrrghlihhnuhigrdhruhdpihhnvghtpedutddrudejjedrvddtrdduheemgeehjeegvddpmhgrihhlfhhrohhmpegrphgrnhhovhesrghsthhrrghlihhnuhigrdhruhdpnhgspghrtghpthhtohepudejpdhrtghpthhtohepshhtrggslhgvsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtohepghhrvghgkhhhsehlihhnuhigfhhouhhnuggrthhiohhnrdhorhhgpdhrtghpthhtoheprghprghnohhvsegrshhtrhgrlhhinhhugidrrhhupdhrtghpthhtohepvgguuhhmrgiivghtsehgohhoghhlvgdrtghomhdprhgtphhtthhopehkuhgsrgeskhgvrhhnvghlrdhorhhgpdhrtghpth htohepphgrsggvnhhisehrvgguhhgrthdrtghomhdprhgtphhtthhopehsrghshhgrlheskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepkhhunhhihihusegrmhgriihonhdrtghomhdprhgtphhtthhopehmkhhhrghlfhgvlhhlrgesphhurhgvshhtohhrrghgvgdrtghomhdprhgtphhtthhopehpthihrggurghvsegrmhgriihonhdruggvpdhrtghpthhtohepkhgvvghstghoohhksegthhhrohhmihhumhdrohhrghdprhgtphhtthhopehlihgrnhhgtghhvghnrdhlihhnuhigsehgmhgrihhlrdgtohhmpdhrtghpthhtohepmhgrrhgtvghlohdrlhgvihhtnhgvrhesghhmrghilhdrtghomhdprhgtphhtthhopehnvghtuggvvhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehlihhnuhigqdhkvghrnhgvlhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehlvhgtqdhprhhojhgvtghtsehlihhnuhigthgvshhtihhnghdrohhrghdprhgtphhtthhopeifihhllhgvmhgssehgohhoghhlvgdrtghomh X-DrWeb-SpamVersion: Vade Retro 01.423.251#02 AS+AV+AP Profile: DRWEB; Bailout: 300 X-AntiVirus: Checked by Dr.Web [MailD: 11.1.19.2307031128, SE: 11.1.12.2210241838, Core engine: 7.00.61.08090, Virus records: 12326436, Updated: 2024-Feb-06 16:36:35 UTC] Content-Type: text/plain; charset="utf-8" From: Eric Dumazet [ Upstream commit 23d05d563b7e7b0314e65c8e882bc27eac2da8e7 ] Once again syzbot is able to crash the kernel in skb_segment() [1] GSO_BY_FRAGS is a forbidden value, but unfortunately the following computation in skb_segment() can reach it quite easily : mss =3D mss * partial_segs; 65535 =3D 3 * 5 * 17 * 257, so many initial values of mss can lead to a bad final result. Make sure to limit segmentation so that the new mss value is smaller than GSO_BY_FRAGS. [1] general protection fault, probably for non-canonical address 0xdffffc000000= 000e: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000070-0x0000000000000077] CPU: 1 PID: 5079 Comm: syz-executor993 Not tainted 6.7.0-rc4-syzkaller-0014= 1-g1ae4cd3cbdd0 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Goo= gle 11/10/2023 RIP: 0010:skb_segment+0x181d/0x3f30 net/core/skbuff.c:4551 Code: 83 e3 02 e9 fb ed ff ff e8 90 68 1c f9 48 8b 84 24 f8 00 00 00 48 8d = 78 70 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c= 0 74 08 3c 03 0f 8e 8a 21 00 00 48 8b 84 24 f8 00 RSP: 0018:ffffc900043473d0 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 0000000000010046 RCX: ffffffff886b1597 RDX: 000000000000000e RSI: ffffffff886b2520 RDI: 0000000000000070 RBP: ffffc90004347578 R08: 0000000000000005 R09: 000000000000ffff R10: 000000000000ffff R11: 0000000000000002 R12: ffff888063202ac0 R13: 0000000000010000 R14: 000000000000ffff R15: 0000000000000046 FS: 0000555556e7e380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020010000 CR3: 0000000027ee2000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: udp6_ufo_fragment+0xa0e/0xd00 net/ipv6/udp_offload.c:109 ipv6_gso_segment+0x534/0x17e0 net/ipv6/ip6_offload.c:120 skb_mac_gso_segment+0x290/0x610 net/core/gso.c:53 __skb_gso_segment+0x339/0x710 net/core/gso.c:124 skb_gso_segment include/net/gso.h:83 [inline] validate_xmit_skb+0x36c/0xeb0 net/core/dev.c:3626 __dev_queue_xmit+0x6f3/0x3d60 net/core/dev.c:4338 dev_queue_xmit include/linux/netdevice.h:3134 [inline] packet_xmit+0x257/0x380 net/packet/af_packet.c:276 packet_snd net/packet/af_packet.c:3087 [inline] packet_sendmsg+0x24c6/0x5220 net/packet/af_packet.c:3119 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0xd5/0x180 net/socket.c:745 __sys_sendto+0x255/0x340 net/socket.c:2190 __do_sys_sendto net/socket.c:2202 [inline] __se_sys_sendto net/socket.c:2198 [inline] __x64_sys_sendto+0xe0/0x1b0 net/socket.c:2198 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b RIP: 0033:0x7f8692032aa9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 d1 19 00 00 90 48 89 f8 48 89 f7 = 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff f= f 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff8d685418 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f8692032aa9 RDX: 0000000000010048 RSI: 00000000200000c0 RDI: 0000000000000003 RBP: 00000000000f4240 R08: 0000000020000540 R09: 0000000000000014 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff8d685480 R13: 0000000000000001 R14: 00007fff8d685480 R15: 0000000000000003 Modules linked in: Reviewed-by: Willem de Bruijn ---[ end trace 0000000000000000 ]--- RIP: 0010:skb_segment+0x181d/0x3f30 net/core/skbuff.c:4551 Code: 83 e3 02 e9 fb ed ff ff e8 90 68 1c f9 48 8b 84 24 f8 00 00 00 48 8d = 78 70 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c= 0 74 08 3c 03 0f 8e 8a 21 00 00 48 8b 84 24 f8 00 RSP: 0018:ffffc900043473d0 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 0000000000010046 RCX: ffffffff886b1597 RDX: 000000000000000e RSI: ffffffff886b2520 RDI: 0000000000000070 RBP: ffffc90004347578 R08: 0000000000000005 R09: 000000000000ffff R10: 000000000000ffff R11: 0000000000000002 R12: ffff888063202ac0 R13: 0000000000010000 R14: 000000000000ffff R15: 0000000000000046 FS: 0000555556e7e380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020010000 CR3: 0000000027ee2000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Fixes: 3953c46c3ac7 ("sk_buff: allow segmenting based on frag sizes") Signed-off-by: Eric Dumazet Cc: Marcelo Ricardo Leitner Reviewed-by: Willem de Bruijn Link: https://lore.kernel.org/r/20231212164621.4131800-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin Signed-off-by: Alexey Panov --- net/core/skbuff.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 8a819d0a7bfb..d4bd10f8723d 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4213,8 +4213,9 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, /* GSO partial only requires that we trim off any excess that * doesn't fit into an MSS sized block, so take care of that * now. + * Cap len to not accidentally hit GSO_BY_FRAGS. */ - partial_segs =3D len / mss; + partial_segs =3D min(len, GSO_BY_FRAGS - 1U) / mss; if (partial_segs > 1) mss *=3D partial_segs; else --=20 2.30.2