From: Yonghong Song <yonghong.song@linux.dev>
To: Jerome Marchand <jmarchan@redhat.com>, bpf@vger.kernel.org
Cc: Martin KaFai Lau <martin.lau@linux.dev>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/2] bpf: Specify access type of bpf_sysctl_get_name args
Date: Thu, 19 Jun 2025 10:32:37 -0700 [thread overview]
Message-ID: <38415904-6af7-41ef-9963-fe60cc6560ba@linux.dev> (raw)
In-Reply-To: <20250619140603.148942-2-jmarchan@redhat.com>
On 6/19/25 7:06 AM, Jerome Marchand wrote:
> The second argument of bpf_sysctl_get_name() helper is a pointer to a
> buffer that is being written to. However that isn't specify in the
> prototype.
>
> Until commit 37cce22dbd51a ("bpf: verifier: Refactor helper access
> type tracking"), all helper accesses were considered as a possible
> write access by the verifier, so no big harm was done. However, since
> then, the verifier might make wrong asssumption about the content of
> that address which might lead it to make faulty optimizations (such as
> removing code that was wrongly labeled dead). This is what happens in
> test_sysctl selftest to the tests related to sysctl_get_name.
>
> Add MEM_WRITE flag the second argument of bpf_sysctl_get_name().
>
> Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
You can carry previous ACK if there is no big change. Ack again here.
Acked-by: Yonghong Song <yonghong.song@linux.dev>
next prev parent reply other threads:[~2025-06-19 17:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-19 14:06 [PATCH v3 0/2] " Jerome Marchand
2025-06-19 14:06 ` [PATCH v3 1/2] " Jerome Marchand
2025-06-19 17:32 ` Yonghong Song [this message]
2025-06-19 14:06 ` [PATCH v3 2/2] selftests/bpf: Convert test_sysctl to prog_tests Jerome Marchand
2025-06-19 17:33 ` Yonghong Song
2025-06-24 5:00 ` [PATCH v3 0/2] bpf: Specify access type of bpf_sysctl_get_name args patchwork-bot+netdevbpf
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