{"id":"CVE-2026-99033","revision":"e1d1b14cb3cf45a19be01fa766b992dd","records":[{"revision":"e1d1b14cb3cf45a19be01fa766b992dd","observedAt":"2026-10-23T16:01:20.601+00:00","statement":{"source":"cve-program","id":"CVE-2026-99033","aliases":[],"title":"net/packet: guard the ll header push in packet_rcv_spkt()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/packet: guard the ll header push in packet_rcv_spkt()\n\npacket_rcv_spkt() restores the link layer header with\n\n\tskb_push(skb, skb->data - skb_mac_header(skb));\n\nThat subtraction is only meaningful when the device actually has a link\nlayer header. packet_rcv() and tpacket_rcv() both wrap it in\ndev_has_header(), which is also the predicate the block comment at the\ntop of the file states the restore in terms of; packet_rcv_spkt() does\nnot. commit d549699048b4 (\"net/packet: fix packet receive on L3\ndevices without visible hard header\") introduced the helper and changed\nthe two call sites, and this one stayed behind.\n\nA device without a visible ll header can leave skb->mac_header at the\n0xFFFF sentinel that __alloc_skb() initialises it to. A CAN skb does:\ninit_can_skb() sets pkt_type and ip_summed but does not reset the\nheaders, and commit 9f10374bb024 (\"can: remove private CAN skb\nheadroom infrastructure\") dropped the skb_reset_*_header() calls that\nused to be there. skb_mac_header() is then 0xFFFF, the length becomes\na large negative number and skb_push() reports it through\nskb_under_panic() -- from softirq context, so it is a full system panic\neven with panic_on_oops=0:\n\n skbuff: skb_under_panic: text:ffffffff8bd21bc1 len:-65455 put:-65471 head:... data:... tail:0x50 end:0x180 dev:can0\n kernel BUG at net/core/skbuff.c:214!\n RIP: 0010:skb_panic+0x50/0x60\n Call Trace:\n \n skb_push+0x38/0x40\n packet_rcv_spkt+0xe1/0x170\n __netif_receive_skb_core.constprop.0+0x7e8/0xd30\n ...\n Kernel panic - not syncing: Fatal exception in interrupt\n\nThe socket type is reachable: packet_create() accepts SOCK_PACKET\nalongside SOCK_RAW and SOCK_DGRAM behind the same CAP_NET_RAW check,\nand neither the socket length nor a capability check keeps it away\nfrom a CAN interface.\n\nThe missing skb_reset_*_header() calls in init_can_skb() are a\nregression in their own right and are being fixed separately, but a\npacket socket should not turn a link layer that did not initialise its\nmac header into a kernel panic. Guard the push the way the other two\nreceive paths do.\n\nTested on v7.3-rc5 under QEMU with a slcan device on a pty, which is\nthe driver RX path: vcan does not reproduce it, because can_send()\nresets the headers on the way out. One SOCK_PACKET socket bound to\ncan0 and one frame written into the line discipline panics an\nunpatched kernel with the trace above; the same image with this patch\nprints no panic and powers off normally. Both kernels are this tree,\ndefconfig plus CONFIG_CAN_SLCAN=y, differing only in this hunk.","state":0,"publishedAt":"2026-10-23T12:21:37.662+00:00","modifiedAt":"2026-10-23T12:21:37.662+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/packet/af_packet.c\"\n ],\n \"versions\": [\n {\n \"version\": \"d549699048b4b5c22dd710455bcdb76966e55aa3\",\n \"lessThan\": \"d8a24b9e1774a93943caf68d48c5e17be432220b\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d549699048b4b5c22dd710455bcdb76966e55aa3\",\n \"lessThan\": \"31c7b15b3716e8d0dad58d2c3cdf321dfd06f4be\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d549699048b4b5c22dd710455bcdb76966e55aa3\",\n \"lessThan\": \"3efe0e0944157fdd2072b4dc7eb0491a317ed272\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d549699048b4b5c22dd710455bcdb76966e55aa3\",\n \"lessThan\": \"00fbf71e74115f7628fc0880b855434b1e70c40c\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d549699048b4b5c22dd710455bcdb76966e55aa3\",\n \"lessThan\": \"28bc1ef699610ee09ce3d46a00552f5a0a0144bd\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"dadddde259a19105ee69e788835f4d4552767aa9\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"5.9.13\",\n \"lessThan\": \"5.10\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/packet/af_packet.c\"\n ],\n \"versions\": [\n {\n \"version\": \"5.10\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"5.10\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.160\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.113\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.57\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2.11\",\n \"lessThanOrEqual\": \"7.2.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.3\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/d8a24b9e1774a93943caf68d48c5e17be432220b","https://git.kernel.org/stable/c/31c7b15b3716e8d0dad58d2c3cdf321dfd06f4be","https://git.kernel.org/stable/c/3efe0e0944157fdd2072b4dc7eb0491a317ed272","https://git.kernel.org/stable/c/00fbf71e74115f7628fc0880b855434b1e70c40c","https://git.kernel.org/stable/c/28bc1ef699610ee09ce3d46a00552f5a0a0144bd"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99033","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-99033","identifiers":["CVE-2026-99033"]},"retained":false,"historicalAffected":[]}],"coverage":[]}