From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 36214 invoked by alias); 11 Jun 2018 00:18:13 -0000 Mailing-List: contact elfutils-devel-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Post: List-Help: List-Subscribe: Sender: elfutils-devel-owner@sourceware.org Received: (qmail 36180 invoked by uid 89); 11 Jun 2018 00:18:11 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Checked: by ClamAV 0.99.4 on sourceware.org X-Virus-Found: No X-Spam-SWARE-Status: No, score=-26.9 required=5.0 tests=BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,RCVD_IN_DNSWL_NONE,SPF_PASS autolearn=ham version=3.3.2 spammy= X-Spam-Status: No, score=-26.9 required=5.0 tests=BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,RCVD_IN_DNSWL_NONE,SPF_PASS autolearn=ham version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on sourceware.org X-Spam-Level: X-HELO: gnu.wildebeest.org Received: from wildebeest.demon.nl (HELO gnu.wildebeest.org) (212.238.236.112) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 11 Jun 2018 00:18:07 +0000 Received: from tarox.wildebeest.org (tarox.wildebeest.org [172.31.17.39]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by gnu.wildebeest.org (Postfix) with ESMTPSA id 2F12830008C1; Mon, 11 Jun 2018 02:18:04 +0200 (CEST) Received: by tarox.wildebeest.org (Postfix, from userid 1000) id DAA57433732B; Mon, 11 Jun 2018 02:18:04 +0200 (CEST) From: Mark Wielaard To: elfutils-devel@sourceware.org Cc: Mark Wielaard Subject: [PATCH] readelf: Fix bounds check in print_form_data. Date: Mon, 11 Jun 2018 00:18:00 -0000 Message-Id: <1528676283-13515-1-git-send-email-mark@klomp.org> X-Mailer: git-send-email 1.8.3.1 X-Spam-Flag: NO X-IsSubscribed: yes X-SW-Source: 2018-q2/txt/msg00199.txt.bz2 The afl fuzzer found that we did a wrong check in print_form_data when comparing the remaining bytes in the buffer to an (unsigned) value read. We were casting the value to ptrdiff_t which is a signed value and so might turn a really big unsigned value into a negative number. Since we know the difference between readendp and readp is zero or greater, we should cast the pointer difference to size_t (and unsigned type) instead before comparing with the unsigned value. Signed-off-by: Mark Wielaard --- src/ChangeLog | 5 +++++ src/readelf.c | 14 +++++++------- 2 files changed, 12 insertions(+), 7 deletions(-) diff --git a/src/ChangeLog b/src/ChangeLog index 8ebb5fb..6484b9a 100644 --- a/src/ChangeLog +++ b/src/ChangeLog @@ -1,3 +1,8 @@ +2018-06-10 Mark Wielaard + + * readelf.c (print_form_data): Don't cast value to ptrdiff_t, cast + ptrdiff_t to size_t. + 2018-06-08 Mark Wielaard * readelf.c (print_debug_rnglists_section): Calculate max_entries diff --git a/src/readelf.c b/src/readelf.c index bbaaf96..fbda6c1 100644 --- a/src/readelf.c +++ b/src/readelf.c @@ -7880,7 +7880,7 @@ print_form_data (Dwarf *dbg, int form, const unsigned char *readp, if (readendp - readp < 1) goto invalid_data; get_uleb128 (val, readp, readendp); - if (readendp - readp < (ptrdiff_t) val) + if ((size_t) (readendp - readp) < val) goto invalid_data; print_bytes (val, readp); readp += val; @@ -7890,7 +7890,7 @@ print_form_data (Dwarf *dbg, int form, const unsigned char *readp, if (readendp - readp < 1) goto invalid_data; val = *readp++; - if (readendp - readp < (ptrdiff_t) val) + if ((size_t) (readendp - readp) < val) goto invalid_data; print_bytes (val, readp); readp += val; @@ -7900,7 +7900,7 @@ print_form_data (Dwarf *dbg, int form, const unsigned char *readp, if (readendp - readp < 2) goto invalid_data; val = read_2ubyte_unaligned_inc (dbg, readp); - if (readendp - readp < (ptrdiff_t) val) + if ((size_t) (readendp - readp) < val) goto invalid_data; print_bytes (val, readp); readp += val; @@ -7910,7 +7910,7 @@ print_form_data (Dwarf *dbg, int form, const unsigned char *readp, if (readendp - readp < 2) goto invalid_data; val = read_4ubyte_unaligned_inc (dbg, readp); - if (readendp - readp < (ptrdiff_t) val) + if ((size_t) (readendp - readp) < val) goto invalid_data; print_bytes (val, readp); readp += val; @@ -7941,7 +7941,7 @@ print_form_data (Dwarf *dbg, int form, const unsigned char *readp, case DW_FORM_strp: case DW_FORM_line_strp: case DW_FORM_strp_sup: - if (readendp - readp < (ptrdiff_t) offset_len) + if ((size_t) (readendp - readp) < offset_len) goto invalid_data; if (offset_len == 8) val = read_8ubyte_unaligned_inc (dbg, readp); @@ -7965,7 +7965,7 @@ print_form_data (Dwarf *dbg, int form, const unsigned char *readp, break; case DW_FORM_sec_offset: - if (readendp - readp < (ptrdiff_t) offset_len) + if ((size_t) (readendp - readp) < offset_len) goto invalid_data; if (offset_len == 8) val = read_8ubyte_unaligned_inc (dbg, readp); @@ -7988,7 +7988,7 @@ print_form_data (Dwarf *dbg, int form, const unsigned char *readp, { readp = data->d_buf + str_offsets_base + val; readendp = data->d_buf + data->d_size; - if (readendp - readp < (ptrdiff_t) offset_len) + if ((size_t) (readendp - readp) < offset_len) str = "???"; else { -- 1.8.3.1