ghsa-g33r-c4mc-9962
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
net: Add rx_skb of kfree_skb to raw_tp_null_args[].
Yan Zhai reported a BPF prog could trigger a null-ptr-deref [0] in trace_kfree_skb if the prog does not check if rx_sk is NULL.
Commit c53795d48ee8 ("net: add rx_sk to trace_kfree_skb") added rx_sk to trace_kfree_skb, but rx_sk is optional and could be NULL.
Let's add kfree_skb to raw_tp_null_args[] to let the BPF verifier validate such a prog and prevent the issue.
Now we fail to load such a prog:
libbpf: prog 'drop': -- BEGIN PROG LOAD LOG -- 0: R1=ctx() R10=fp0 ; int BPF_PROG(drop, struct sk_buff skb, void location, @ kfree_skb_sk_null.bpf.c:21 0: (79) r3 = (u64 )(r1 +24) func 'kfree_skb' arg3 has btf_id 5253 type STRUCT 'sock' 1: R1=ctx() R3_w=trusted_ptr_or_null_sock(id=1) ; bpf_printk("sk: %d, %d\n", sk, sk->__sk_common.skc_family); @ kfree_skb_sk_null.bpf.c:24 1: (69) r4 = (u16 )(r3 +16) R3 invalid mem access 'trusted_ptr_or_null_' processed 2 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0 -- END PROG LOAD LOG --
Note this fix requires commit 838a10bd2ebf ("bpf: Augment raw_tp arguments with PTR_MAYBE_NULL").
[0]: BUG: kernel NULL pointer dereference, address: 0000000000000010 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page PGD 0 P4D 0 PREEMPT SMP RIP: 0010:bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d Call Trace: ? __die+0x1f/0x60 ? page_fault_oops+0x148/0x420 ? search_bpf_extables+0x5b/0x70 ? fixup_exception+0x27/0x2c0 ? exc_page_fault+0x75/0x170 ? asm_exc_page_fault+0x22/0x30 ? bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d bpf_trace_run4+0x68/0xd0 ? unix_stream_connect+0x1f4/0x6f0 sk_skb_reason_drop+0x90/0x120 unix_stream_connect+0x1f4/0x6f0 __sys_connect+0x7f/0xb0 __x64_sys_connect+0x14/0x20 do_syscall_64+0x47/0xc30 entry_SYSCALL_64_after_hwframe+0x4b/0x53
{
"affected": [],
"aliases": [
"CVE-2025-21852"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-03-12T10:15:17Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: Add rx_skb of kfree_skb to raw_tp_null_args[].\n\nYan Zhai reported a BPF prog could trigger a null-ptr-deref [0]\nin trace_kfree_skb if the prog does not check if rx_sk is NULL.\n\nCommit c53795d48ee8 (\"net: add rx_sk to trace_kfree_skb\") added\nrx_sk to trace_kfree_skb, but rx_sk is optional and could be NULL.\n\nLet\u0027s add kfree_skb to raw_tp_null_args[] to let the BPF verifier\nvalidate such a prog and prevent the issue.\n\nNow we fail to load such a prog:\n\n libbpf: prog \u0027drop\u0027: -- BEGIN PROG LOAD LOG --\n 0: R1=ctx() R10=fp0\n ; int BPF_PROG(drop, struct sk_buff *skb, void *location, @ kfree_skb_sk_null.bpf.c:21\n 0: (79) r3 = *(u64 *)(r1 +24)\n func \u0027kfree_skb\u0027 arg3 has btf_id 5253 type STRUCT \u0027sock\u0027\n 1: R1=ctx() R3_w=trusted_ptr_or_null_sock(id=1)\n ; bpf_printk(\"sk: %d, %d\\n\", sk, sk-\u003e__sk_common.skc_family); @ kfree_skb_sk_null.bpf.c:24\n 1: (69) r4 = *(u16 *)(r3 +16)\n R3 invalid mem access \u0027trusted_ptr_or_null_\u0027\n processed 2 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0\n -- END PROG LOAD LOG --\n\nNote this fix requires commit 838a10bd2ebf (\"bpf: Augment raw_tp\narguments with PTR_MAYBE_NULL\").\n\n[0]:\nBUG: kernel NULL pointer dereference, address: 0000000000000010\n PF: supervisor read access in kernel mode\n PF: error_code(0x0000) - not-present page\nPGD 0 P4D 0\nPREEMPT SMP\nRIP: 0010:bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d\nCall Trace:\n \u003cTASK\u003e\n ? __die+0x1f/0x60\n ? page_fault_oops+0x148/0x420\n ? search_bpf_extables+0x5b/0x70\n ? fixup_exception+0x27/0x2c0\n ? exc_page_fault+0x75/0x170\n ? asm_exc_page_fault+0x22/0x30\n ? bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d\n bpf_trace_run4+0x68/0xd0\n ? unix_stream_connect+0x1f4/0x6f0\n sk_skb_reason_drop+0x90/0x120\n unix_stream_connect+0x1f4/0x6f0\n __sys_connect+0x7f/0xb0\n __x64_sys_connect+0x14/0x20\n do_syscall_64+0x47/0xc30\n entry_SYSCALL_64_after_hwframe+0x4b/0x53",
"id": "GHSA-g33r-c4mc-9962",
"modified": "2025-03-13T18:32:21Z",
"published": "2025-03-12T12:30:58Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-21852"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4dba79c1e7aad6620bbb707b6c4459380fd90860"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5da7e15fb5a12e78de974d8908f348e279922ce9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f579afacd0a66971fc8481f30d2d377e230a8342"
}
],
"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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