From: Yiyang Chen <chenyy23@mails.tsinghua.edu.cn>
To: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: Yiyang Chen <chenyy23@mails.tsinghua.edu.cn>,
John Fastabend <john.fastabend@gmail.com>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>,
Emil Tsalapatis <emil@etsalapatis.com>,
Shuah Khan <shuah@kernel.org>,
bpf@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH bpf-next 0/2] bpf: Validate byte type for helper stack reads
Date: Mon, 13 Jul 2026 06:16:10 +0000 [thread overview]
Message-ID: <cover.1783920884.git.chenyy23@mails.tsinghua.edu.cn> (raw)
The verifier checks helper memory arguments byte by byte, but its scalar
spill fast path only checks the slot-wide spill marker. For a CAP_BPF load,
a narrow scalar spill can therefore make an untouched sibling byte appear
initialized when the sibling is passed to a helper.
Patch 1 makes the fast path require STACK_SPILL for the byte being checked.
Patch 2 adds verifier_spill_fill coverage for a CAP_BPF map update helper
reading an invalid sibling byte.
Yiyang Chen (2):
bpf: Check byte type when validating helper stack reads
selftests/bpf: Cover helper reads of invalid spill siblings
kernel/bpf/verifier.c | 3 +-
.../selftests/bpf/progs/verifier_spill_fill.c | 33 +++++++++++++++++++
2 files changed, 35 insertions(+), 1 deletion(-)
base-commit: 9a3a07d06e7d74f4aecc51396c771149336ac55d
--
2.34.1
next reply other threads:[~2026-07-13 6:16 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-13 6:16 Yiyang Chen [this message]
2026-07-13 6:16 ` [PATCH bpf-next 1/2] bpf: Check byte type when validating " Yiyang Chen
2026-07-13 21:22 ` Eduard Zingerman
2026-07-14 18:05 ` Yiyang Chen
2026-07-13 6:16 ` [PATCH bpf-next 2/2] selftests/bpf: Cover helper reads of invalid spill siblings Yiyang Chen
2026-07-13 7:17 ` bot+bpf-ci
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