From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: "Kumar Kartikeya Dwivedi" <memxor@gmail.com>, <bpf@vger.kernel.org>
Cc: "Andrii Nakryiko" <andrii@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Eduard Zingerman" <eddyz87@gmail.com>,
"Emil Tsalapatis" <emil@etsalapatis.com>, <kkd@meta.com>,
<kernel-team@meta.com>
Subject: Re: [PATCH bpf-next v1 1/3] bpf: Check fastcall contract for helper and kfunc stack buffers
Date: Thu, 24 Sep 2026 05:55:09 +0000 [thread overview]
Message-ID: <DLNBBR9198NM.1OAVB1QAY5UG8@gmail.com> (raw)
In-Reply-To: <20260923084201.2437625-2-memxor@gmail.com>
On Wed, Sep 23, 2026 at 10:41 AM Kumar Kartikeya Dwivedi <memxor@gmail.com> wrote:
> + /*
> + * Helpers and kfuncs can access stack slots without going through the
> + * regular stack read/write paths, including when raw mode is disabled.
> + */
> + if (access_size)
> + check_fastcall_stack_contract(env, state, env->insn_idx, min_off);
can we do it once in check_stack_access_within_bounds() ?
Both check_mem_access() and check_stack_range_initialized() call it
first, and it already has the frame that owns the slot and min_off.
Then the other four check_fastcall_stack_contract() calls can go
and patch 2 is not needed.
next prev parent reply other threads:[~2026-09-24 5:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-23 8:41 [PATCH bpf-next v1 0/3] Fix fastcall rewrite with indirect stack accesses Kumar Kartikeya Dwivedi
2026-09-23 8:41 ` [PATCH bpf-next v1 1/3] bpf: Check fastcall contract for helper and kfunc stack buffers Kumar Kartikeya Dwivedi
2026-09-24 5:55 ` Alexei Starovoitov [this message]
2026-09-23 8:41 ` [PATCH bpf-next v1 2/3] bpf: Check fastcall contract of the frame a stack read targets Kumar Kartikeya Dwivedi
2026-09-23 8:41 ` [PATCH bpf-next v1 3/3] selftests/bpf: Test fastcall rewrite with indirect stack accesses Kumar Kartikeya Dwivedi
2026-09-23 9:33 ` bot+bpf-ci
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