From: Carlos Llamas <cmllamas@google.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: mykyta.yatsenko5@gmail.com, Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <martin.lau@linux.dev>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>,
kernel-team@android.com, linux-kernel@vger.kernel.org,
Mykyta Yatsenko <yatsenko@meta.com>,
"open list:BPF [GENERAL] (Safe Dynamic Programs and Tools)"
<bpf@vger.kernel.org>
Subject: Re: [PATCH v2] libbpf: fix UAF in strset__add_str()
Date: Mon, 18 May 2026 04:59:10 +0000 [thread overview]
Message-ID: <agqcnt81eI16gOYr@google.com> (raw)
In-Reply-To: <CAEf4BzZMoWdgYFGXwT9kkZ1TKbe9ZB=XKJCuKy0+2uqzSMDMUw@mail.gmail.com>
On Fri, May 15, 2026 at 03:08:47PM -0700, Andrii Nakryiko wrote:
> I agree that this is a usability problem, but I'd handle it by
> recalculating s pointer to correct one if it happens to be coming from
> invalidated strs_data. Something along the lines of:
>
> const char *old_data = set->strs_data;
> size_t old_data_len = set->strs_data_len;
>
> p = strset_add_str_mem(...);
> if (!p)
> return -ENOMEM;
>
> if (p != old_data && s >= old_data && s < old_data + old_data_len)
> s = p + (s - old_data);
>
>
> At this point s will be correct even if it was invalidated.
>
> pw-bot: cr
Oh right, that totally works. I've tested the changes and will send a
new patch. Obviously 'p' was meant to be 'set->strs_data' in the check.
Thanks,
--
Carlos Llamas
next prev parent reply other threads:[~2026-05-18 4:59 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <89d34016-cf82-4beb-989c-e4fc2e3cd29e@gmail.com>
2026-05-15 4:47 ` [PATCH v2] libbpf: fix UAF in strset__add_str() Carlos Llamas
2026-05-15 22:08 ` Andrii Nakryiko
2026-05-18 4:59 ` Carlos Llamas [this message]
2026-05-18 5:05 ` [PATCH v3] " Carlos Llamas
2026-05-18 17:36 ` Andrii Nakryiko
2026-05-22 18:35 ` Andrii Nakryiko
2026-05-22 18:50 ` Carlos Llamas
2026-05-23 16:27 ` [PATCH v4] " Carlos Llamas
2026-05-23 17:05 ` bot+bpf-ci
2026-05-28 21:31 ` Andrii Nakryiko
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