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Thu, 29 Aug 2024 17:42:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724953364; bh=Rp6otyrq1s70AfuJSm1rv8h2cgFz+vWWyi+WpWNJo0k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=h9S7C4y+C06tQyD+Sl51neSMfzNbO3H7+XqTB+9IpLWNA5lP+7o39gvHMaHYMTSM1 NOme1U8VxqRTfLT9XS/9uBRx6l7NB72LK9SCN1+L+uvRjNIyIAZAFWeULC4Hz2BJm7 qfp5elwqfey2Rzwir5hsz1BcEG4n4MeOej78lpi6juzXR7URC5jNrQNEPXgOQ7fhif rTKpnnCjGuyYxfLhZecA2brCZkio51MjpJbulavW8CtHl3fiwLCJxk1z/jqJgwJGEy UXSe7/zUDwVUrveZGzktpl0G1JOYrU7B+QGYubKYXXQyOdSc6vsex6cDe+5LPPE7cw ol9ipOaSf/sig== From: Andrii Nakryiko To: 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, Andrii Nakryiko , Eduard Zingerman Subject: [PATCH v7 bpf-next 03/10] lib/buildid: take into account e_phoff when fetching program headers Date: Thu, 29 Aug 2024 10:42:25 -0700 Message-ID: <20240829174232.3133883-4-andrii@kernel.org> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20240829174232.3133883-1-andrii@kernel.org> References: <20240829174232.3133883-1-andrii@kernel.org> MIME-Version: 1.0 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: ABB62180021 X-Stat-Signature: jp1a58km6yu3k1oitsjnx77rxrh6df6c X-Rspam-User: X-HE-Tag: 1724953366-748236 X-HE-Meta: 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 ztJo+A9W B1Elc3oeG5Mb2XSyK6ULq2bniE/7Rw/d2CeQe4cOcD5ndmETZ2hHXD7Ei+U1CXXT8D1QyGrgQgF54fI5D7Vch8aWmk8UkL3QLUmV6h/phMylCrO5Ynv4tGpHk2ovsfmHvfltKu0eV1qCRd2Qpf67aE5X4Qt9CaEgiyK2yZ4LsscbVaxZyTW74u/h1PHlwL3V/oIUbi9HXP5iNtYal82MUA7m/jwf9f7mLg1sw/LlKCZEiUDJo8LgCIlAgvgzvNvYQfwtcJ0k7rei92t/V6BiGnTXBAGnZZOFEQM9G7sYQzXBFs3A= 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: Current code assumption is that program (segment) headers are following ELF header immediately. This is a common case, but is not guaranteed. So take into account e_phoff field of the ELF header when accessing program headers. Reviewed-by: Eduard Zingerman Reported-by: Alexey Dobriyan Signed-off-by: Andrii Nakryiko --- lib/buildid.c | 35 ++++++++++++++++------------------- 1 file changed, 16 insertions(+), 19 deletions(-) diff --git a/lib/buildid.c b/lib/buildid.c index bfe00b66b1e8..7fb08a1d98bd 100644 --- a/lib/buildid.c +++ b/lib/buildid.c @@ -213,28 +213,26 @@ static int get_build_id_32(struct freader *r, unsigned char *build_id, __u32 *si { const Elf32_Ehdr *ehdr; const Elf32_Phdr *phdr; - __u32 phnum, i; + __u32 phnum, phoff, i; ehdr = freader_fetch(r, 0, sizeof(Elf32_Ehdr)); if (!ehdr) return r->err; - /* - * FIXME - * Neither ELF spec nor ELF loader require that program headers - * start immediately after ELF header. - */ - if (ehdr->e_phoff != sizeof(Elf32_Ehdr)) - return -EINVAL; - /* subsequent freader_fetch() calls invalidate pointers, so remember locally */ phnum = READ_ONCE(ehdr->e_phnum); + phoff = READ_ONCE(ehdr->e_phoff); + /* only supports phdr that fits in one page */ if (phnum > (PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr)) return -EINVAL; + /* check that phoff is not large enough to cause an overflow */ + if (phoff + phnum * sizeof(Elf32_Phdr) < phoff) + return -EINVAL; + for (i = 0; i < phnum; ++i) { - phdr = freader_fetch(r, i * sizeof(Elf32_Phdr), sizeof(Elf32_Phdr)); + phdr = freader_fetch(r, phoff + i * sizeof(Elf32_Phdr), sizeof(Elf32_Phdr)); if (!phdr) return r->err; @@ -252,27 +250,26 @@ static int get_build_id_64(struct freader *r, unsigned char *build_id, __u32 *si const Elf64_Ehdr *ehdr; const Elf64_Phdr *phdr; __u32 phnum, i; + __u64 phoff; ehdr = freader_fetch(r, 0, sizeof(Elf64_Ehdr)); if (!ehdr) return r->err; - /* - * FIXME - * Neither ELF spec nor ELF loader require that program headers - * start immediately after ELF header. - */ - if (ehdr->e_phoff != sizeof(Elf64_Ehdr)) - return -EINVAL; - /* subsequent freader_fetch() calls invalidate pointers, so remember locally */ phnum = READ_ONCE(ehdr->e_phnum); + phoff = READ_ONCE(ehdr->e_phoff); + /* only supports phdr that fits in one page */ if (phnum > (PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr)) return -EINVAL; + /* check that phoff is not large enough to cause an overflow */ + if (phoff + phnum * sizeof(Elf64_Phdr) < phoff) + return -EINVAL; + for (i = 0; i < phnum; ++i) { - phdr = freader_fetch(r, i * sizeof(Elf64_Phdr), sizeof(Elf64_Phdr)); + phdr = freader_fetch(r, phoff + i * sizeof(Elf64_Phdr), sizeof(Elf64_Phdr)); if (!phdr) return r->err;