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From: Hillf Danton <hdanton@sina.com>
To: syzbot <syzbot+bfde3bef047a81b8fde6@syzkaller.appspotmail.com>
Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [net?] KASAN: use-after-free Read in __skb_flow_dissect (3)
Date: Fri, 19 Jan 2024 12:49:58 +0800	[thread overview]
Message-ID: <20240119044958.1809-1-hdanton@sina.com> (raw)
In-Reply-To: <000000000000498a02060de59162@google.com>

On Mon, 01 Jan 2024 09:18:16 -0800
> syzbot found the following issue on:
> 
> HEAD commit:    f5837722ffec Merge tag 'mm-hotfixes-stable-2023-12-27-15-0..
> git tree:       upstream
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=122dfc65e80000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git  master

--- x/net/core/flow_dissector.c
+++ y/net/core/flow_dissector.c
@@ -1165,9 +1165,13 @@ proto_again:
 	case htons(ETH_P_IP): {
 		const struct iphdr *iph;
 		struct iphdr _iph;
+		const unsigned char *buf = data;
+
+		if (2 != buf[0])
+			_iph.ihl = 1;
 
 		iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph);
-		if (!iph || iph->ihl < 5) {
+		if (nhoff < 0 || !iph || iph->ihl < 5) {
 			fdret = FLOW_DISSECT_RET_OUT_BAD;
 			break;
 		}
--

  parent reply	other threads:[~2024-01-19  4:50 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-01 17:18 syzbot
2024-01-17 11:23 ` Hillf Danton
2024-01-17 11:58   ` syzbot
2024-01-17 13:14 ` Hillf Danton
2024-01-17 13:35   ` syzbot
2024-01-17 22:51 ` Hillf Danton
2024-01-17 23:16   ` syzbot
2024-01-17 23:43 ` Hillf Danton
2024-01-18  0:18   ` syzbot
2024-01-18  2:33 ` Hillf Danton
2024-01-18  2:55   ` syzbot
2024-01-18  4:33 ` Hillf Danton
2024-01-18  4:47   ` syzbot
2024-01-18 11:17 ` Hillf Danton
2024-01-18 11:47   ` syzbot
2024-01-18 12:08 ` Hillf Danton
2024-01-18 12:31   ` syzbot
2024-01-18 13:17 ` Hillf Danton
2024-01-18 13:40   ` syzbot
2024-01-18 22:15 ` Hillf Danton
2024-01-18 22:34   ` syzbot
2024-01-19  4:49 ` Hillf Danton [this message]
2024-01-19  5:22   ` syzbot
2024-01-19  7:38 ` Hillf Danton
2024-01-19  8:01   ` syzbot
2024-01-19 10:31 ` Hillf Danton
2024-01-19 10:47   ` syzbot
2024-01-19 11:47 ` Hillf Danton
2024-01-19 12:07   ` syzbot
2024-02-20 13:05 ` [syzbot] KASAN: use-after-free Read in __skb_flow_dissect syzbot
     [not found] <20240220130510.GC19387@breakpoint.cc>
2024-02-20 13:27 ` [syzbot] [net?] KASAN: use-after-free Read in __skb_flow_dissect (3) syzbot

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