ghsa-r2cq-rw93-xwch
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
skmsg: Skip zero length skb in sk_msg_recvmsg
When running BPF selftests (./test_progs -t sockmap_basic) on a Loongarch platform, the following kernel panic occurs:
[...] Oops[#1]: CPU: 22 PID: 2824 Comm: test_progs Tainted: G OE 6.10.0-rc2+ #18 Hardware name: LOONGSON Dabieshan/Loongson-TC542F0, BIOS Loongson-UDK2018 ... ... ra: 90000000048bf6c0 sk_msg_recvmsg+0x120/0x560 ERA: 9000000004162774 copy_page_to_iter+0x74/0x1c0 CRMD: 000000b0 (PLV0 -IE -DA +PG DACF=CC DACM=CC -WE) PRMD: 0000000c (PPLV0 +PIE +PWE) EUEN: 00000007 (+FPE +SXE +ASXE -BTE) ECFG: 00071c1d (LIE=0,2-4,10-12 VS=7) ESTAT: 00010000 [PIL] (IS= ECode=1 EsubCode=0) BADV: 0000000000000040 PRID: 0014c011 (Loongson-64bit, Loongson-3C5000) Modules linked in: bpf_testmod(OE) xt_CHECKSUM xt_MASQUERADE xt_conntrack Process test_progs (pid: 2824, threadinfo=0000000000863a31, task=...) Stack : ... Call Trace: [<9000000004162774>] copy_page_to_iter+0x74/0x1c0 [<90000000048bf6c0>] sk_msg_recvmsg+0x120/0x560 [<90000000049f2b90>] tcp_bpf_recvmsg_parser+0x170/0x4e0 [<90000000049aae34>] inet_recvmsg+0x54/0x100 [<900000000481ad5c>] sock_recvmsg+0x7c/0xe0 [<900000000481e1a8>] __sys_recvfrom+0x108/0x1c0 [<900000000481e27c>] sys_recvfrom+0x1c/0x40 [<9000000004c076ec>] do_syscall+0x8c/0xc0 [<9000000003731da4>] handle_syscall+0xc4/0x160 Code: ... ---[ end trace 0000000000000000 ]--- Kernel panic - not syncing: Fatal exception Kernel relocated by 0x3510000 .text @ 0x9000000003710000 .data @ 0x9000000004d70000 .bss @ 0x9000000006469400 ---[ end Kernel panic - not syncing: Fatal exception ]--- [...]
This crash happens every time when running sockmap_skb_verdict_shutdown subtest in sockmap_basic.
This crash is because a NULL pointer is passed to page_address() in the sk_msg_recvmsg(). Due to the different implementations depending on the architecture, page_address(NULL) will trigger a panic on Loongarch platform but not on x86 platform. So this bug was hidden on x86 platform for a while, but now it is exposed on Loongarch platform. The root cause is that a zero length skb (skb->len == 0) was put on the queue.
This zero length skb is a TCP FIN packet, which was sent by shutdown(), invoked in test_sockmap_skb_verdict_shutdown():
shutdown(p1, SHUT_WR);
In this case, in sk_psock_skb_ingress_enqueue(), num_sge is zero, and no page is put to this sge (see sg_set_page in sg_set_page), but this empty sge is queued into ingress_msg list.
And in sk_msg_recvmsg(), this empty sge is used, and a NULL page is got by sg_page(sge). Pass this NULL page to copy_page_to_iter(), which passes it to kmap_local_page() and to page_address(), then kernel panics.
To solve this, we should skip this zero length skb. So in sk_msg_recvmsg(), if copy is zero, that means it's a zero length skb, skip invoking copy_page_to_iter(). We are using the EFAULT return triggered by copy_page_to_iter to check for is_fin in tcp_bpf.c.
{
"affected": [],
"aliases": [
"CVE-2024-41048"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-07-29T15:15:13Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nskmsg: Skip zero length skb in sk_msg_recvmsg\n\nWhen running BPF selftests (./test_progs -t sockmap_basic) on a Loongarch\nplatform, the following kernel panic occurs:\n\n [...]\n Oops[#1]:\n CPU: 22 PID: 2824 Comm: test_progs Tainted: G OE 6.10.0-rc2+ #18\n Hardware name: LOONGSON Dabieshan/Loongson-TC542F0, BIOS Loongson-UDK2018\n ... ...\n ra: 90000000048bf6c0 sk_msg_recvmsg+0x120/0x560\n ERA: 9000000004162774 copy_page_to_iter+0x74/0x1c0\n CRMD: 000000b0 (PLV0 -IE -DA +PG DACF=CC DACM=CC -WE)\n PRMD: 0000000c (PPLV0 +PIE +PWE)\n EUEN: 00000007 (+FPE +SXE +ASXE -BTE)\n ECFG: 00071c1d (LIE=0,2-4,10-12 VS=7)\n ESTAT: 00010000 [PIL] (IS= ECode=1 EsubCode=0)\n BADV: 0000000000000040\n PRID: 0014c011 (Loongson-64bit, Loongson-3C5000)\n Modules linked in: bpf_testmod(OE) xt_CHECKSUM xt_MASQUERADE xt_conntrack\n Process test_progs (pid: 2824, threadinfo=0000000000863a31, task=...)\n Stack : ...\n Call Trace:\n [\u003c9000000004162774\u003e] copy_page_to_iter+0x74/0x1c0\n [\u003c90000000048bf6c0\u003e] sk_msg_recvmsg+0x120/0x560\n [\u003c90000000049f2b90\u003e] tcp_bpf_recvmsg_parser+0x170/0x4e0\n [\u003c90000000049aae34\u003e] inet_recvmsg+0x54/0x100\n [\u003c900000000481ad5c\u003e] sock_recvmsg+0x7c/0xe0\n [\u003c900000000481e1a8\u003e] __sys_recvfrom+0x108/0x1c0\n [\u003c900000000481e27c\u003e] sys_recvfrom+0x1c/0x40\n [\u003c9000000004c076ec\u003e] do_syscall+0x8c/0xc0\n [\u003c9000000003731da4\u003e] handle_syscall+0xc4/0x160\n Code: ...\n ---[ end trace 0000000000000000 ]---\n Kernel panic - not syncing: Fatal exception\n Kernel relocated by 0x3510000\n .text @ 0x9000000003710000\n .data @ 0x9000000004d70000\n .bss @ 0x9000000006469400\n ---[ end Kernel panic - not syncing: Fatal exception ]---\n [...]\n\nThis crash happens every time when running sockmap_skb_verdict_shutdown\nsubtest in sockmap_basic.\n\nThis crash is because a NULL pointer is passed to page_address() in the\nsk_msg_recvmsg(). Due to the different implementations depending on the\narchitecture, page_address(NULL) will trigger a panic on Loongarch\nplatform but not on x86 platform. So this bug was hidden on x86 platform\nfor a while, but now it is exposed on Loongarch platform. The root cause\nis that a zero length skb (skb-\u003elen == 0) was put on the queue.\n\nThis zero length skb is a TCP FIN packet, which was sent by shutdown(),\ninvoked in test_sockmap_skb_verdict_shutdown():\n\n\tshutdown(p1, SHUT_WR);\n\nIn this case, in sk_psock_skb_ingress_enqueue(), num_sge is zero, and no\npage is put to this sge (see sg_set_page in sg_set_page), but this empty\nsge is queued into ingress_msg list.\n\nAnd in sk_msg_recvmsg(), this empty sge is used, and a NULL page is got by\nsg_page(sge). Pass this NULL page to copy_page_to_iter(), which passes it\nto kmap_local_page() and to page_address(), then kernel panics.\n\nTo solve this, we should skip this zero length skb. So in sk_msg_recvmsg(),\nif copy is zero, that means it\u0027s a zero length skb, skip invoking\ncopy_page_to_iter(). We are using the EFAULT return triggered by\ncopy_page_to_iter to check for is_fin in tcp_bpf.c.",
"id": "GHSA-r2cq-rw93-xwch",
"modified": "2025-02-03T18:30:38Z",
"published": "2024-07-29T15:30:42Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-41048"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/195b7bcdfc5adc5b2468f279dd9eb7eebd2e7632"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b180739b45a38b4caa88fe16bb5273072e6613dc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f0c18025693707ec344a70b6887f7450bf4c826b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f8bd689f37f4198a4c61c4684f591ba639595b97"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fb61d7b9fb6ef0032de469499a54dab4c7260d0d"
}
],
"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"
}
]
}
Sightings
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