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Fri, 23 Aug 2024 16:23:00 -0700 (PDT) Received: from [192.168.0.235] ([38.34.87.7]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-7cd9abfd5b1sm3722097a12.0.2024.08.23.16.22.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Aug 2024 16:23:00 -0700 (PDT) Message-ID: Subject: Re: [PATCH v6 bpf-next 00/10] Harden and extend ELF build ID parsing logic From: Eduard Zingerman To: Andrii Nakryiko , bpf@vger.kernel.org Cc: linux-mm@kvack.org, akpm@linux-foundation.org, adobriyan@gmail.com, shakeel.butt@linux.dev, hannes@cmpxchg.org, ak@linux.intel.com, osandov@osandov.com, song@kernel.org, jannh@google.com, linux-fsdevel@vger.kernel.org, willy@infradead.org Date: Fri, 23 Aug 2024 16:22:55 -0700 In-Reply-To: <20240814185417.1171430-1-andrii@kernel.org> References: <20240814185417.1171430-1-andrii@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.52.4 (3.52.4-1.fc40) MIME-Version: 1.0 X-Rspam-User: X-Stat-Signature: jwn3fjdbdsnzaqk5jgxkg69mdh6a4siw X-Rspamd-Queue-Id: A99631C000F X-Rspamd-Server: rspam11 X-HE-Tag: 1724455381-740909 X-HE-Meta: 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 YWqAYk// H0bYCSySS2kV5HW0rWLkU8KeskjtT4Wc94NcwOYnyrquwuSfv0BQxPAdHhHRVJ3ih6SaGHFB3i5ESZibas9Y4C81kSAmwtKrvw2lwDnhO+ep4R+Ldb+eQxvq7h7ZqI5MdWHcUXgMajHAKlx6ROlgWF4PFmlNP//lKK5KymAyajr5xe9S9dR3cOFvX3dHjQYjNHz0vUwYWIfuppid75qMfL9FcyTNTwAYy/ZhijMlmxqd4wuCmPsnKA6SQp2xi4m57WtEUukxsghbGY4dGs72DWfKs4m79yqHGO34Jyt4xP5tmDT25VC/FDJ3D7uBXOA33AGpG2YZC8TAlj4FfkRxF1jLb+HT7WYvuadTZZ6fIMcJ4+Ig= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 2024-08-14 at 11:54 -0700, Andrii Nakryiko wrote: [...] > Andrii Nakryiko (10): > lib/buildid: harden build ID parsing logic > lib/buildid: add single folio-based file reader abstraction > lib/buildid: take into account e_phoff when fetching program headers > lib/buildid: remove single-page limit for PHDR search > lib/buildid: rename build_id_parse() into build_id_parse_nofault() > lib/buildid: implement sleepable build_id_parse() API > lib/buildid: don't limit .note.gnu.build-id to the first page in ELF Never worked with lib/buildid before, so not sure how valuable my input is. Anyways: - I compared the resulting parser with ELF specification and available documentation for buildid, all seems correct. (with a small caveat that ELF defines Elf{32,64}_Ehdr->e_ehsize field to encode actual size of the elf header, and e_phentsize to encode actual size of the program header. Parser uses sizeof(Elf{32,64}_{Ehdr,Phdr}) instead, and this is how it was before, so probably does not matter). - The `freader` abstraction nicely hides away difference between sleepable and non-sleepable contexts. (with a caveat, that freader_get_folio() uses read_cache_folio() which is documented as expecting mapping->invalidate_lock to be held. I assume that this is true for vma's passed to build_id_parse(), right?) For what it's worth, full patch-set looks good to me. Reviewed-by: Eduard Zingerman [...]