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CVE-2026-98647

bpf: Fix divide-by-zero in btf_struct_walk() PUBLISHED

Description (CNA)

In 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: <TASK> 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 </TASK> 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 (CNA)

Vendor / productVersions
Linux / Linuxaffected 9c5f8a1008a121e4c6b24af211034e24b0b63081 before 1ea3820937f8022e044c41c6e95c84b02741b45f; affected 9c5f8a1008a121e4c6b24af211034e24b0b63081 before 172756f02663ad45c889c001c1a8cb4082a01a05; affected 9c5f8a1008a121e4c6b24af211034e24b0b63081 before 934e9ba9f8d05656a48624710be67ca4dc8482e6; affected 9c5f8a1008a121e4c6b24af211034e24b0b63081 before 63af086cb5fa6f72fd924f86bea4c2194da663a2; affected 9c5f8a1008a121e4c6b24af211034e24b0b63081 before 8eb4cd72daad3a9ee63d2281bbdd16ce6d9406b1; affected 9c5f8a1008a121e4c6b24af211034e24b0b63081 before b8fa56722e9c43bcd59c51fe4c7edd5f4158a11b; affected 9c5f8a1008a121e4c6b24af211034e24b0b63081 before b0b3dc66529676228cb938cbcad66920f735c223
Linux / Linuxaffected 5.8; unaffected 0 before 5.8; unaffected 5.15.222 through 5.15.*; unaffected 6.1.189 through 6.1.*; unaffected 6.6.158 through 6.6.*; unaffected 6.12.112 through 6.12.*; unaffected 6.18.55 through 6.18.*; unaffected 7.2.9 through 7.2.*; unaffected 7.3 through *

CWE

No CWE identifiers supplied.

References