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 ED0F54D8C6 for ; Wed, 24 Jul 2024 22:52:36 +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=1721861557; cv=none; b=MuejeI0J4LBF73QK5+h2AyckPNH/wpY3LVNGWSs3dwAf51HCh0V0w5mIAbQ5zQj/+Wmw2tOU8h6eMcL3KoshdBs8uxag7nuDE3q1ozJFptYUTxqNXTZUnNva0kZLIuicbjKRLZ1W/GIIrGZsAMq1kHGJHLy7NN+xljbaSK/x4+M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721861557; c=relaxed/simple; bh=ntgIIpn+tzkBcO08o2+RKeRyEZVireJUIPte90Dh4v8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kfeueVRljcKLZNEOit4EXqncwD220bZpU6SG3EuI+Z1OiftgHSv4qyC2NT+nHHT/bqH7G5XfPmq1FFi/Zs5OZn+7HDdgLBtNj16QA1YWT1PJaT3JdebirVjg6ucCZgEOjDp3ZSMx6vwWQWGrJXtSXqUywHo1EVR+SJhQT1os+8M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DQwpSIMi; 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="DQwpSIMi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA922C32781; Wed, 24 Jul 2024 22:52:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1721861556; bh=ntgIIpn+tzkBcO08o2+RKeRyEZVireJUIPte90Dh4v8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DQwpSIMimhn7FkBAz2vr8LNKFVUQN83+hiSazx2Qt70eqWzSTOLdzhmnRy2wauKDC XprAOeoDwPz6pMgua9jNTDdtoZJnpt50jO3m0QcetBXcmIA8QAdtdsI5KaOKIjZ1AC w9vkqW0aq5enF+8I1XGYtiyOYNBVO/F+V2o/u7oBAXDrbIay1V+rNz9TI4T8pfamGA 0/u2trA0alBnBrJLjiK+Ydm9nA3nQzoZlHqXaCoZWbNDKkQOkoDFHiL2USGDbGWZRQ 9YorGVDfMlYftfv7v+SXMpkIo61qyCkdZza2jvCfu6uIaes9fzSh9ctcz/3Phbjfze Utnqd2yaZxa9A== 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, Andrii Nakryiko Subject: [PATCH v2 bpf-next 07/10] lib/buildid: harden build ID parsing logic some more Date: Wed, 24 Jul 2024 15:52:07 -0700 Message-ID: <20240724225210.545423-8-andrii@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240724225210.545423-1-andrii@kernel.org> References: <20240724225210.545423-1-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 Harden build ID parsing logic some more, adding explicit READ_ONCE() when fetching values that we then use to check correctness and various note iteration invariants. Suggested-by: Andi Kleen Signed-off-by: Andrii Nakryiko --- lib/buildid.c | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-) diff --git a/lib/buildid.c b/lib/buildid.c index 419966d88cd5..7e36a32fbb90 100644 --- a/lib/buildid.c +++ b/lib/buildid.c @@ -158,7 +158,7 @@ static int parse_build_id(struct freader *r, unsigned char *build_id, __u32 *siz const char note_name[] = "GNU"; const size_t note_name_sz = sizeof(note_name); u64 build_id_off, new_offs, note_end = note_offs + note_size; - u32 build_id_sz; + u32 build_id_sz, name_sz, desc_sz; const Elf32_Nhdr *nhdr; const char *data; @@ -171,14 +171,15 @@ static int parse_build_id(struct freader *r, unsigned char *build_id, __u32 *siz if (!nhdr) return r->err; - if (nhdr->n_type == BUILD_ID && - nhdr->n_namesz == note_name_sz && - !strcmp((char *)(nhdr + 1), note_name) && - nhdr->n_descsz > 0 && - nhdr->n_descsz <= BUILD_ID_SIZE_MAX) { + name_sz = READ_ONCE(nhdr->n_namesz); + desc_sz = READ_ONCE(nhdr->n_descsz); + if (READ_ONCE(nhdr->n_type) == BUILD_ID && + name_sz == note_name_sz && + !strncmp((char *)(nhdr + 1), note_name, note_name_sz) && + desc_sz > 0 && desc_sz <= BUILD_ID_SIZE_MAX) { build_id_off = note_offs + sizeof(Elf32_Nhdr) + ALIGN(note_name_sz, 4); - build_id_sz = nhdr->n_descsz; + build_id_sz = desc_sz; /* freader_fetch() will invalidate nhdr pointer */ data = freader_fetch(r, build_id_off, build_id_sz); @@ -192,8 +193,7 @@ static int parse_build_id(struct freader *r, unsigned char *build_id, __u32 *siz return 0; } - new_offs = note_offs + sizeof(Elf32_Nhdr) + - ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4); + new_offs = note_offs + sizeof(Elf32_Nhdr) + ALIGN(name_sz, 4) + ALIGN(desc_sz, 4); if (new_offs <= note_offs) /* overflow */ break; note_offs = new_offs; @@ -214,7 +214,7 @@ static int get_build_id_32(struct freader *r, unsigned char *build_id, __u32 *si return r->err; /* subsequent freader_fetch() calls invalidate pointers, so remember locally */ - phnum = ehdr->e_phnum; + phnum = READ_ONCE(ehdr->e_phnum); phoff = READ_ONCE(ehdr->e_phoff); /* set upper bound on amount of segments (phdrs) we iterate */ @@ -226,8 +226,9 @@ static int get_build_id_32(struct freader *r, unsigned char *build_id, __u32 *si if (!phdr) return r->err; - if (phdr->p_type == PT_NOTE && - !parse_build_id(r, build_id, size, phdr->p_offset, phdr->p_filesz)) + if (READ_ONCE(phdr->p_type) == PT_NOTE && + !parse_build_id(r, build_id, size, + READ_ONCE(phdr->p_offset), READ_ONCE(phdr->p_filesz))) return 0; } return -EINVAL; @@ -246,7 +247,7 @@ static int get_build_id_64(struct freader *r, unsigned char *build_id, __u32 *si return r->err; /* subsequent freader_fetch() calls invalidate pointers, so remember locally */ - phnum = ehdr->e_phnum; + phnum = READ_ONCE(ehdr->e_phnum); phoff = READ_ONCE(ehdr->e_phoff); /* set upper bound on amount of segments (phdrs) we iterate */ @@ -258,8 +259,9 @@ static int get_build_id_64(struct freader *r, unsigned char *build_id, __u32 *si if (!phdr) return r->err; - if (phdr->p_type == PT_NOTE && - !parse_build_id(r, build_id, size, phdr->p_offset, phdr->p_filesz)) + if (READ_ONCE(phdr->p_type) == PT_NOTE && + !parse_build_id(r, build_id, size, + READ_ONCE(phdr->p_offset), READ_ONCE(phdr->p_filesz))) return 0; } -- 2.43.0