GHSA-P98X-GG62-CXQ2
Vulnerability from github – Published: 2026-10-18 18:31 – Updated: 2026-10-18 18:31In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix divide-by-zero in btf_struct_walk()
When an access goes past the struct and the last member is a flexible array, btf_struct_walk() folds the offset back into a single element with (off - moff) % t->size, but never checks that the element type has a size.
BTF takes an empty struct, so this in program BTF
/* event could be empty */
struct event {
#ifdef HAVE_TIMESTAMP __u64 ts; #endif };
struct batch {
int nr;
struct event events[];
};
divides by zero at prog load time. Getting there needs a PTR_TO_BTF_ID that is not MEM_ALLOC, e.g. a plain read of a local kptr stashed in a map from a sleepable program.
Oops: divide error: 0000 [#1] SMP KASAN PTI RIP: 0010:btf_struct_walk+0x53f/0x1570 Call Trace: btf_struct_access+0x42a/0xcd0 check_ptr_to_btf_access+0x4dc/0x1160 check_mem_access+0x3a45/0x8740 check_load_mem+0x36a/0xd10 do_check_common+0x3ef0/0xb210 bpf_check+0x6d3b/0x8580 bpf_prog_load+0xf7c/0x2720 __sys_bpf+0xa83/0x3690 __x64_sys_bpf+0xc7/0x150 x64_sys_call+0x1f3f/0x27e0 do_syscall_64+0xe5/0x610 entry_SYSCALL_64_after_hwframe+0x76/0x7e
Reject a zero-sized element type. The fixed array path in the same function already bails out on the same thing:
btf_struct_walk()
...
/* skip empty array */
if (moff == mtrue_end)
continue;
msize /= total_nelems;
{
"affected": [],
"aliases": [
"CVE-2026-98647"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-18T16:17:17Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix divide-by-zero in btf_struct_walk()\n\nWhen an access goes past the struct and the last member is a flexible\narray, btf_struct_walk() folds the offset back into a single element with\n(off - moff) % t-\u003esize, but never checks that the element type has a size.\n\nBTF takes an empty struct, so this in program BTF\n\n\t/* event could be empty */\n\tstruct event {\n #ifdef HAVE_TIMESTAMP\n\t\t__u64 ts;\n #endif\n\t};\n\n\tstruct batch {\n\t\tint nr;\n\t\tstruct event events[];\n\t};\n\ndivides by zero at prog load time. Getting there needs a PTR_TO_BTF_ID that\nis not MEM_ALLOC, e.g. a plain read of a local kptr stashed in a map from a\nsleepable program.\n\nOops: divide error: 0000 [#1] SMP KASAN PTI\nRIP: 0010:btf_struct_walk+0x53f/0x1570\nCall Trace:\n \u003cTASK\u003e\n btf_struct_access+0x42a/0xcd0\n check_ptr_to_btf_access+0x4dc/0x1160\n check_mem_access+0x3a45/0x8740\n check_load_mem+0x36a/0xd10\n do_check_common+0x3ef0/0xb210\n bpf_check+0x6d3b/0x8580\n bpf_prog_load+0xf7c/0x2720\n __sys_bpf+0xa83/0x3690\n __x64_sys_bpf+0xc7/0x150\n x64_sys_call+0x1f3f/0x27e0\n do_syscall_64+0xe5/0x610\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n \u003c/TASK\u003e\n\nReject a zero-sized element type. The fixed array path in the same function\nalready bails out on the same thing:\n\n\tbtf_struct_walk()\n\t...\n\t\t/* skip empty array */\n\t\tif (moff == mtrue_end)\n\t\t\tcontinue;\n\n\t\tmsize /= total_nelems;",
"id": "GHSA-p98x-gg62-cxq2",
"modified": "2026-10-18T18:31:58Z",
"published": "2026-10-18T18:31:58Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98647"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/172756f02663ad45c889c001c1a8cb4082a01a05"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1ea3820937f8022e044c41c6e95c84b02741b45f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/63af086cb5fa6f72fd924f86bea4c2194da663a2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8eb4cd72daad3a9ee63d2281bbdd16ce6d9406b1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/934e9ba9f8d05656a48624710be67ca4dc8482e6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b0b3dc66529676228cb938cbcad66920f735c223"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b8fa56722e9c43bcd59c51fe4c7edd5f4158a11b"
}
],
"schema_version": "1.4.0",
"severity": []
}
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