Re: [PATCH bpf-next v3 3/6] bpf: Disallow !kprobe_write_ctx progs tail-calling kprobe_write_ctx progs
From: bot+bpf-ci@kernel.org
Date: 2026-03-03 16:01:47
Also in:
bpf, linux-kselftest, lkml
quoted hunk ↗ jump to hunk
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c
[ ... ]
+ switch (match) {
+ case BPF_MAP_OWNER_MATCH_FOR_INIT:
+ if (owner->kprobe_write_ctx != aux->kprobe_write_ctx)
+ return false;
+ break;
+
+ case BPF_MAP_OWNER_MATCH_FOR_UPDATE:
+ if (!owner->kprobe_write_ctx && aux->kprobe_write_ctx)
+ return false;
+ break;
+ }
In the v1 review, Alexei Starovoitov asked for strict conformance
both ways rather than one-directional validation:
"Don't be fancy. Require strict conformance both ways
in *all* patches."
https://lore.kernel.org/bpf/CAADnVQ+-V0-1i8_+CYpK7G0CnV-2n8e9Szv43yM3Az197eL_0A@mail.gmail.com/ (local)
The BPF_MAP_OWNER_MATCH_FOR_UPDATE case still uses one-directional
matching, rejecting only !owner->kprobe_write_ctx && aux->kprobe_write_ctx
but allowing the reverse. Was this an intentional design choice, and
if so, should the changelog note the disagreement?
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/22630000544