GHSA-XHM6-WPWJ-QM56
Vulnerability from github – Published: 2024-03-18 12:30 – Updated: 2025-03-10 18:31In the Linux kernel, the following vulnerability has been resolved:
llc: Drop support for ETH_P_TR_802_2.
syzbot reported an uninit-value bug below. [0]
llc supports ETH_P_802_2 (0x0004) and used to support ETH_P_TR_802_2 (0x0011), and syzbot abused the latter to trigger the bug.
write$tun(r0, &(0x7f0000000040)={@val={0x0, 0x11}, @val, @mpls={[], @llc={@snap={0xaa, 0x1, ')', "90e5dd"}}}}, 0x16)
llc_conn_handler() initialises local variables {saddr,daddr}.mac based on skb in llc_pdu_decode_sa()/llc_pdu_decode_da() and passes them to __llc_lookup().
However, the initialisation is done only when skb->protocol is htons(ETH_P_802_2), otherwise, __llc_lookup_established() and __llc_lookup_listener() will read garbage.
The missing initialisation existed prior to commit 211ed865108e ("net: delete all instances of special processing for token ring").
It removed the part to kick out the token ring stuff but forgot to close the door allowing ETH_P_TR_802_2 packets to sneak into llc_rcv().
Let's remove llc_tr_packet_type and complete the deprecation.
[0]: BUG: KMSAN: uninit-value in __llc_lookup_established+0xe9d/0xf90 __llc_lookup_established+0xe9d/0xf90 __llc_lookup net/llc/llc_conn.c:611 [inline] llc_conn_handler+0x4bd/0x1360 net/llc/llc_conn.c:791 llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206 __netif_receive_skb_one_core net/core/dev.c:5527 [inline] __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5641 netif_receive_skb_internal net/core/dev.c:5727 [inline] netif_receive_skb+0x58/0x660 net/core/dev.c:5786 tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1555 tun_get_user+0x53af/0x66d0 drivers/net/tun.c:2002 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048 call_write_iter include/linux/fs.h:2020 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x8ef/0x1490 fs/read_write.c:584 ksys_write+0x20f/0x4c0 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __x64_sys_write+0x93/0xd0 fs/read_write.c:646 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b
Local variable daddr created at: llc_conn_handler+0x53/0x1360 net/llc/llc_conn.c:783 llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206
CPU: 1 PID: 5004 Comm: syz-executor994 Not tainted 6.6.0-syzkaller-14500-g1c41041124bd #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
{
"affected": [],
"aliases": [
"CVE-2024-26635"
],
"database_specific": {
"cwe_ids": [
"CWE-909"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-03-18T11:15:10Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nllc: Drop support for ETH_P_TR_802_2.\n\nsyzbot reported an uninit-value bug below. [0]\n\nllc supports ETH_P_802_2 (0x0004) and used to support ETH_P_TR_802_2\n(0x0011), and syzbot abused the latter to trigger the bug.\n\n write$tun(r0, \u0026(0x7f0000000040)={@val={0x0, 0x11}, @val, @mpls={[], @llc={@snap={0xaa, 0x1, \u0027)\u0027, \"90e5dd\"}}}}, 0x16)\n\nllc_conn_handler() initialises local variables {saddr,daddr}.mac\nbased on skb in llc_pdu_decode_sa()/llc_pdu_decode_da() and passes\nthem to __llc_lookup().\n\nHowever, the initialisation is done only when skb-\u003eprotocol is\nhtons(ETH_P_802_2), otherwise, __llc_lookup_established() and\n__llc_lookup_listener() will read garbage.\n\nThe missing initialisation existed prior to commit 211ed865108e\n(\"net: delete all instances of special processing for token ring\").\n\nIt removed the part to kick out the token ring stuff but forgot to\nclose the door allowing ETH_P_TR_802_2 packets to sneak into llc_rcv().\n\nLet\u0027s remove llc_tr_packet_type and complete the deprecation.\n\n[0]:\nBUG: KMSAN: uninit-value in __llc_lookup_established+0xe9d/0xf90\n __llc_lookup_established+0xe9d/0xf90\n __llc_lookup net/llc/llc_conn.c:611 [inline]\n llc_conn_handler+0x4bd/0x1360 net/llc/llc_conn.c:791\n llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206\n __netif_receive_skb_one_core net/core/dev.c:5527 [inline]\n __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5641\n netif_receive_skb_internal net/core/dev.c:5727 [inline]\n netif_receive_skb+0x58/0x660 net/core/dev.c:5786\n tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1555\n tun_get_user+0x53af/0x66d0 drivers/net/tun.c:2002\n tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048\n call_write_iter include/linux/fs.h:2020 [inline]\n new_sync_write fs/read_write.c:491 [inline]\n vfs_write+0x8ef/0x1490 fs/read_write.c:584\n ksys_write+0x20f/0x4c0 fs/read_write.c:637\n __do_sys_write fs/read_write.c:649 [inline]\n __se_sys_write fs/read_write.c:646 [inline]\n __x64_sys_write+0x93/0xd0 fs/read_write.c:646\n do_syscall_x64 arch/x86/entry/common.c:51 [inline]\n do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82\n entry_SYSCALL_64_after_hwframe+0x63/0x6b\n\nLocal variable daddr created at:\n llc_conn_handler+0x53/0x1360 net/llc/llc_conn.c:783\n llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206\n\nCPU: 1 PID: 5004 Comm: syz-executor994 Not tainted 6.6.0-syzkaller-14500-g1c41041124bd #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023",
"id": "GHSA-xhm6-wpwj-qm56",
"modified": "2025-03-10T18:31:49Z",
"published": "2024-03-18T12:30:35Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26635"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/165ad1e22779685c3ed3dd349c6c4c632309cc62"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/660c3053d992b68fee893a0e9ec9159228cffdc6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9ccdef19cf9497c2803b005369668feb91cacdfd"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b8e8838f82f332ae80c643dbb1ca4418d0628097"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c0fe2fe7a5a291dfcf6dc64301732c8d3dc6a828"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/df57fc2f2abf548aa889a36ab0bdcc94a75399dc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e3f9bed9bee261e3347131764e42aeedf1ffea61"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f1f34a515fb1e25e85dee94f781e7869ae351fb8"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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