From: Andi Kleen <ak@linux.intel.com>
To: Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, adobriyan@gmail.com,
shakeel.butt@linux.dev, hannes@cmpxchg.org, osandov@osandov.com,
song@kernel.org, jannh@google.com, stable@vger.kernel.org
Subject: Re: [PATCH v3 bpf-next 01/10] lib/buildid: harden build ID parsing logic
Date: Tue, 30 Jul 2024 21:04:58 -0700 [thread overview]
Message-ID: <Zqm36i0Afe48193Z@tassilo> (raw)
In-Reply-To: <20240730203914.1182569-2-andrii@kernel.org>
> while (note_offs + sizeof(Elf32_Nhdr) < note_size) {
> Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs);
>
> + name_sz = READ_ONCE(nhdr->n_namesz);
> + desc_sz = READ_ONCE(nhdr->n_descsz);
> if (nhdr->n_type == BUILD_ID &&
> - nhdr->n_namesz == sizeof("GNU") &&
> - !strcmp((char *)(nhdr + 1), "GNU") &&
> - nhdr->n_descsz > 0 &&
> - nhdr->n_descsz <= BUILD_ID_SIZE_MAX) {
> - memcpy(build_id,
> - note_start + note_offs +
> - ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr),
> - nhdr->n_descsz);
> - memset(build_id + nhdr->n_descsz, 0,
> - BUILD_ID_SIZE_MAX - nhdr->n_descsz);
> + name_sz == note_name_sz &&
> + strcmp((char *)(nhdr + 1), note_name) == 0 &&
Doesn't the strcmp need a boundary check to be inside note_size too?
Other it may read into the next page, which could be unmapped, causing a fault.
Given it's unlikely that this happen, and the end has guard pages,
but there are some users of set_memory_np.
You could just move the later checks earlier.
The rest looks good to me.
-Andi
next prev parent reply other threads:[~2024-07-31 4:05 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-30 20:39 [PATCH v3 bpf-next 00/10] Harden and extend ELF build ID parsing logic Andrii Nakryiko
2024-07-30 20:39 ` [PATCH v3 bpf-next 01/10] lib/buildid: harden " Andrii Nakryiko
2024-07-31 4:04 ` Andi Kleen [this message]
2024-07-31 21:54 ` Andrii Nakryiko
2024-07-30 20:39 ` [PATCH v3 bpf-next 02/10] lib/buildid: add single page-based file reader abstraction Andrii Nakryiko
2024-07-30 20:39 ` [PATCH v3 bpf-next 03/10] lib/buildid: take into account e_phoff when fetching program headers Andrii Nakryiko
2024-07-30 20:39 ` [PATCH v3 bpf-next 04/10] lib/buildid: remove single-page limit for PHDR search Andrii Nakryiko
2024-07-30 20:39 ` [PATCH v3 bpf-next 05/10] lib/buildid: rename build_id_parse() into build_id_parse_nofault() Andrii Nakryiko
2024-07-30 20:39 ` [PATCH v3 bpf-next 06/10] lib/buildid: implement sleepable build_id_parse() API Andrii Nakryiko
2024-07-31 21:56 ` Andrii Nakryiko
2024-08-05 18:30 ` Shakeel Butt
2024-07-30 20:39 ` [PATCH v3 bpf-next 07/10] lib/buildid: don't limit .note.gnu.build-id to the first page in ELF Andrii Nakryiko
2024-07-30 20:39 ` [PATCH v3 bpf-next 08/10] bpf: decouple stack_map_get_build_id_offset() from perf_callchain_entry Andrii Nakryiko
2024-07-30 20:39 ` [PATCH v3 bpf-next 09/10] bpf: wire up sleepable bpf_get_stack() and bpf_get_task_stack() helpers Andrii Nakryiko
2024-07-30 20:39 ` [PATCH v3 bpf-next 10/10] selftests/bpf: add build ID tests Andrii Nakryiko
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