From: Alexei Starovoitov Date: Wed, 15 Apr 2026 15:40:48 +0000 (-0700) Subject: Merge branch 'bpf-arg-tracking-for-imprecise-multi-offset-bpf_st-stx' X-Git-Url: http://git.ipfire.org/index.cgi?a=commitdiff_plain;h=2865c3f3f620fa78294522665f470e1bf0e64d47;p=thirdparty%2Fkernel%2Flinux.git Merge branch 'bpf-arg-tracking-for-imprecise-multi-offset-bpf_st-stx' Eduard Zingerman says: ==================== bpf: arg tracking for imprecise/multi-offset BPF_ST/STX When the static arg tracking analysis encounters a store through a pointer with imprecise or multi-offset destination, it must use weak updates (join) instead of strong updates (overwrite) for the affected at_stack slots. At runtime only one slot is actually written; the others retain their old values. Two cases are addressed: - BPF_STX, handled by spill_to_stack(). It was gated on `dst_is_local_fp = (frame == depth)`, which missed ARG_IMPRECISE pointers entirely. - BPF_ST, handled by clear_stack_for_all_offs(). It delegates to clear_overlapping_stack_slots() which unconditionally set `at_stack[i] = none`. Change to `at_stack[i] = join(old, none)` when multiple candidate slots exist (cnt != 1), so that untouched slots preserve their tracked values. No veristat diff compared to current master when tested on selftests, sched_ext, cilium and a set of Meta internal programs. This addresses issues reported by sashiko for patch #7 in [1]. [1] https://sashiko.dev/#/patchset/20260410-patch-set-v4-0-5d4eecb343db%40gmail.com Changelog: v2 -> v3: - Use check_add_overflow() in arg_add() (Alexei). - Add missing fixes tag (CI bot). - Remove unused __imm in the selftest (sashiko). v1 -> v2: - Delete the OFF_IMPRECISE constant, always rely on arg_track->cnt == 0 as a marker the offset is imprecise. (Alexei). - Squash all patches together to simplify backporting to 'bpf' branch (Alexei). v1: https://lore.kernel.org/bpf/20260413-stacklive-fixes-v1-0-9f48a9999d6e@gmail.com/T/ v2: https://lore.kernel.org/bpf/20260413-stacklive-fixes-v2-0-ff91c4f8d273@gmail.com/T/ --- ==================== Link: https://patch.msgid.link/20260413-stacklive-fixes-v2-0-398e126e5cf3@gmail.com Signed-off-by: Alexei Starovoitov --- 2865c3f3f620fa78294522665f470e1bf0e64d47