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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?Rf0VGDMZ1AkIWCELGrp7X3uO1FQOKVsrw8/wPdibXeuUZsUP3UQkYYXbZQKG?= =?us-ascii?Q?Xz1V9ZXfomVWF0C1PjqQR/KQyTvG7tCXq0OpJMbshe/sajKLnmyHhiL5ZuKy?= =?us-ascii?Q?fOZZ3398Ut1CC2BIAuAIIZZ4puUv6fN5N99PTHbiqXSQ3lTgvTdIKXOfyOYU?= =?us-ascii?Q?EzFzkV43w4WP7iBNpoYjVKQQFZfIjdxG3Uofju9wR2NFmz1dgoVuZnySnLIM?= =?us-ascii?Q?RgpVF3S1j+jeuCl3TNMbuEyV5S/Ti8kTpK7qp6Lxg7AjHJ//06GSnGNVjLh7?= =?us-ascii?Q?9uKWQjJLGOqbDjZOYHEdMeWzK/yc0OGMAv8RcND+PZYgLl6H/S44OorJJzLY?= =?us-ascii?Q?t/Crxa9CoPHk4x8+Gy9hLyDMb5XsFEikWQAz2IVG/vuSeeOLI7UZ9MNMGls9?= =?us-ascii?Q?Ia6KnhRiN3Qg67MEVdjRkx9QrkcmbYbz1ycqo4arQkLW7CB7Fx62JdCJLE83?= =?us-ascii?Q?IpCX3YAleTGxDWFmVtO3FYRhFaqf70Pmn93ls1OzuzloQzU2wKRA92F9B1Cl?= =?us-ascii?Q?AiflBzFe6zFoE0YX1zep1Xew8M+p22IOseeWYc00I81h/4TOBe31++f3lcgN?= =?us-ascii?Q?P+hRQZHIrHZxWgp+Xm8pPdL5rsLHY+tMGSYvBE9vpfS+SekGIUW0+y2QOpFE?= =?us-ascii?Q?tklOggpGWc3TxojwDPecxVLi+U4FAJgj7W+YgDz/kxI6MpEXhnzRvBfoIAB7?= =?us-ascii?Q?lQ+OMDaw948d/zIw9y0vqVXbqQWehSC8IXedPyKQc55g6fBPVD0qj0SPLtYm?= =?us-ascii?Q?nCADL5m8B9axh2r3hH6v6E2Gp8UABRXeZ0FNBhVyK/fPUlPiS3puRrs2Ce1Y?= =?us-ascii?Q?dTsrI0ZGkO1LTlK7jOzGilmM6KGoTixYCUGrmQOevV3ZFg2Uqvo7q7064WYK?= =?us-ascii?Q?fRp7EPhhH/Lg7iukAlUOVUfqQ2qW6E3yduakSjyU739U51oIOCKQBZh4kSJA?= =?us-ascii?Q?eJogjUgrDVxTkbDfdTZYoTlZFUdaWBjmWAJQt0rEWUw2G/lk4IoRAxRvVdnH?= =?us-ascii?Q?e2HiSVNVyGv4opMhZF/Uc5NjpJIW9/SD4cBszftMy0OOCXONxWt34UvLl6+6?= =?us-ascii?Q?NwG4WqOxUCESuwXH3V35GY6gODHAoJcBM2S3onU1WFhXVvYatKb/0+65hm0Z?= =?us-ascii?Q?9oEI5ak6sXMhzMus7JK3rhcwwEvZa9dwYsxWjngEu8tKCnoZ1f6hInK4G4Eq?= =?us-ascii?Q?hSyynWV5DtxZWM6z4ctlmVD5Q95KbvMkUCPDXxEQfQj+eOXZ8ltdFlgT+YQp?= =?us-ascii?Q?m6keZ33MAEX4GTOlncAKGFx3AO6yDmWl7/fHjTmejdShvMY24eygeoFDiobu?= =?us-ascii?Q?UxiJhiVAMP4saj585jvS77necGl5CEaOSVk9lKAueD7d8Z7rwV5h7O8yGzMS?= =?us-ascii?Q?2TdnUebLXTw6FJDxveU8fUKu6S05QZ/KAB/Li9yCrTwfKD+7E4vZbcPy6or0?= =?us-ascii?Q?b4bDXzH+5NVtJypNnHgKEuNReuRL8+skpmoHowAxMf6Ko/UUtTChZpUejvNI?= =?us-ascii?Q?5FZvCtp+uT5UZtLpGzejGuFYMqsW7GjPBoYqUBQXuUxJXHYNWa2GKnJDKB7F?= =?us-ascii?Q?Nd5Q/3oibxWwmcFFTS3yEUevG+v+LfkV6oH3oFwcC+s8IQ+vnA5d6Co4zDTg?= =?us-ascii?Q?cNkdKNDDIVZYrC2X5DGd2ngKWI7fl8P69be++gsypaj/paAZ1dJQcz8+OOC7?= =?us-ascii?Q?QAt00jD5VKCG2OBaNWObJf7OfnDNUBBX1SDwZum25jGGVFIr?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 195afd94-0569-45a7-4b22-08dee5719426 X-MS-Exchange-CrossTenant-AuthSource: SA3PR12MB7901.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Jul 2026 08:41:51.4469 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: IjR8kZMx/qfClrQMfVDBG7r7DZqVCL4XAcmYDhM54OqZThd8YwjNu9IT4zifdkF5JuUQtVfgLRFREYxHlSFhgA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR12MB8103 On Mon, Jul 13, 2026 at 10:11:06PM +0800, Yizhou Zhao wrote: > ic_bootp_recv() accepts an IP packet whose total length exceeds its UDP > datagram length. This is valid at the IP layer, but DHCP/BOOTP options > belong to the UDP payload. The option parser nevertheless uses the IP > total length as its end boundary. > > Consequently, an on-link attacker that can race a boot-time DHCP exchange > can put DHCP options after the declared UDP payload and have ipconfig > consume them. A QEMU/KVM reproduction with ip=dhcp accepted a forged > DHCPOFFER/DHCPACK with an IP total length of 290 and UDP length of 248; > the tail supplied a netmask and an off-link gateway, causing boot-time > network configuration to fail. > > Use the UDP datagram end as the parser boundary. The receiver already > verifies that the UDP datagram lies within the IP packet, so this retains > normal valid DHCP/BOOTP parsing while excluding the IP-only tail. > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Cc: stable@vger.kernel.org > Reported-by: Yizhou Zhao > Reported-by: Yuxiang Yang > Reported-by: Ao Wang > Reported-by: Xuewei Feng > Reported-by: Qi Li > Reported-by: Ke Xu > Assisted-by: Claude-Code:GLM-5.2-special > Signed-off-by: Yizhou Zhao The code change looks correct, but why frame it as a security fix? Can't an "on-link attacker" forge the UDP payload instead?