CVE-2026-98599

In the Linux kernel, the following vulnerability has been resolved:

bpf: Reject non-negative offsets in stack_slot_obj_get_spi()

bpf_get_spi() computes (-off - 1) / BPF_REG_SIZE using C division,

which truncates toward zero. For off == 0, this produces spi 0, the

same index used by the valid stack slot at fp-8.

stack_slot_obj_get_spi() currently checks alignment and the resulting

spi bounds, but does not reject the non-negative offset itself. It can

therefore validate a PTR_TO_STACK register holding fp+0 against an

iterator stored at fp-8 even though the runtime receives the actual fp+0

pointer. An effectful iterator kfunc can then interpret memory outside

the BPF stack as iterator state.

Reject non-negative offsets before converting the offset to an spi. All

valid stack objects begin at a negative offset from the frame pointer.