From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F0B5C1684BE for ; Tue, 30 Jul 2024 20:39:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722371968; cv=none; b=ceY693Z1RE5BR8hUjP5rdp/hqL+LY/yyWZ6JEQ8wWPvSmA30UZC35u7fxIDcctk8iCKcGLX9XWYHORzd/AwISiqZkokjPd4LTLQ4EijkVTzG/+kSoXF229AlR14IPmbYm9EtN33o3lDv1AymaW6KtzNDKKDbt73dVQJJLmwIrUc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722371968; c=relaxed/simple; bh=dgztIaI7wcUufYQC2M1f2CEzPpb4qtKFeC4HcS1F34s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=UF2jP7DR9bToe72/NDFHkKoPDS2KX+hGvSqG1Humi/Zs80ATnuwj1qWsoV25cqZ+lmw+qwTmSg3ARtPjymEMuQweLEkj9fiCZjFQJUIeWqIErU0qaZ7686C3cOD1ybB62MuejAMSsuE1Rz0Lqu27FDDG0ZZ4d4StOiqNx+Nydvs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JJHHNmm0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JJHHNmm0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 635DDC32782; Tue, 30 Jul 2024 20:39:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722371967; bh=dgztIaI7wcUufYQC2M1f2CEzPpb4qtKFeC4HcS1F34s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JJHHNmm0RMR0lI68DTZjiB1Shtq5MZ1QfO8BeQ7hc3vZ0cTdbz1Q2AR5dSLhMOT+M cDHtRFjC59k8ZM/cy8Y15dooEsrwrZzCEHtkmS55Ph7HFcsfKaMHsc45mMhLpzJ//9 cyCsUBW1oEof2DPgCMNLwCBerVU3wAhvxwxi9uCcjylMui6/QUGx06sOMMeEEMp2zn lTA3faXrcDLFlWKdnkCV+S8opQPU55ht8uQx9kel3yiQszLvmpDVwgrqDoG457104d 3wg83ar9DdMT7ad3I3BUyAmad/M3b48csSLAYWbtjYb1367xyI9fEOdSKgSEoPObat w119lCn4clZzA== 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, Andrii Nakryiko Subject: [PATCH v3 bpf-next 03/10] lib/buildid: take into account e_phoff when fetching program headers Date: Tue, 30 Jul 2024 13:39:07 -0700 Message-ID: <20240730203914.1182569-4-andrii@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240730203914.1182569-1-andrii@kernel.org> References: <20240730203914.1182569-1-andrii@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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. Reported-by: Alexey Dobriyan Signed-off-by: Andrii Nakryiko --- lib/buildid.c | 26 ++++++++------------------ 1 file changed, 8 insertions(+), 18 deletions(-) diff --git a/lib/buildid.c b/lib/buildid.c index 522850f827a5..ba453a3784d1 100644 --- a/lib/buildid.c +++ b/lib/buildid.c @@ -207,27 +207,22 @@ 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; + __u64 phoff; 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; 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; @@ -245,27 +240,22 @@ 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; 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; -- 2.43.0