From patchwork Thu Nov 19 00:53:02 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Don Breazeal X-Patchwork-Id: 9735 Received: (qmail 80516 invoked by alias); 19 Nov 2015 00:53:08 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 80479 invoked by uid 89); 19 Nov 2015 00:53:07 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.2 required=5.0 tests=AWL, BAYES_00, RCVD_IN_DNSWL_LOW, SPF_PASS autolearn=ham version=3.3.2 X-HELO: relay1.mentorg.com Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 19 Nov 2015 00:53:06 +0000 Received: from svr-orw-fem-04.mgc.mentorg.com ([147.34.97.41]) by relay1.mentorg.com with esmtp id 1ZzDTD-0005Ke-MZ from Don_Breazeal@mentor.com for gdb-patches@sourceware.org; Wed, 18 Nov 2015 16:53:03 -0800 Received: from build4-lucid-cs (147.34.91.1) by svr-orw-fem-04.mgc.mentorg.com (147.34.97.41) with Microsoft SMTP Server id 14.3.224.2; Wed, 18 Nov 2015 16:53:03 -0800 Received: by build4-lucid-cs (Postfix, from userid 1905) id EB16141154; Wed, 18 Nov 2015 16:53:02 -0800 (PST) From: Don Breazeal To: Subject: [PATCH] Fix '-data-read-memory-bytes' typo/assertion Date: Wed, 18 Nov 2015 16:53:02 -0800 Message-ID: <1447894382-1469-1-git-send-email-donb@codesourcery.com> MIME-Version: 1.0 X-IsSubscribed: yes This patch fixes a typo in target.c:read_memory_robust, where it calls read_whatever_is_readable with the function arguments in the wrong order. Depending on the address being read, it can cause an xmalloc with a huge size, resulting in an assertion failure, or just read something other than what was requested. The problem only arises when GDB is handling an MI "-data-read-memory-bytes" request and the initial target_read returns an error status. Note that read_memory_robust is only called from the MI code. Function definition: static void read_whatever_is_readable (struct target_ops *ops, const ULONGEST begin, const ULONGEST end, int unit_size, VEC(memory_read_result_s) **result) Function call: read_whatever_is_readable (ops, offset + xfered_total, unit_size, offset + xfered_total + to_read, &result); If we debug gdb, generate the error, and break just before the call to read_whatever_is_readable, we see: # Generate an error by trying to read a bogus address in the GDB # that is under debug. (gdb) interpreter-exec mi "-data-read-memory-bytes 1073741752 216" # GDB-under-debug stops at the breakpoint on the call to # read_whatever_is_readable. Breakpoint 1, read_memory_robust (ops=0xe70150, offset=1073741752, len=216) at /scratch/dbreazea/sandbox/gdb-5611/binutils-gdb/gdb/target.c:1825 1825 read_whatever_is_readable (ops, offset + xfered_total, unit_size, (top) p unit_size $1 = 1 # Step into the function. (top) step read_whatever_is_readable (ops=0xe70150, begin=1073741752, end=1, unit_size=1073741968, result=0x7fffffffdd40) at /scratch/dbreazea/sandbox/gdb-5611/binutils-gdb/gdb/target.c:1658 1658 gdb_byte *buf = (gdb_byte *) xmalloc (end - begin); # unit_size was passed as 'end', and we are going to xmalloc a large # number and assert. (top) p end-begin $2 = 18446744072635809865 (top) c Continuing. "/scratch/dbreazea/sandbox/gdb-5611/binutils-gdb/gdb/utils.c:1072: internal-error: virtual memory exhausted.\nA problem internal to GDB has been detected,\nfurther debugging may prove unreliable.\nQuit this debugging session? (y or n) " # With the fixed version, (end - begin) gives the 'len' passed to # read_memory_robust and specified by -data-read-memory-bytes (top) p end-begin $2 = 216 Tested on native x86_64 Linux with the gdb.mi tests. OK? thanks --Don gdb/ 2015-11-18 Don Breazeal * gdb/target.c (read_memory_robust): Call read_whatever_is_readable with arguments in the correct order. --- gdb/target.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/gdb/target.c b/gdb/target.c index 93786c3..950a1b7 100644 --- a/gdb/target.c +++ b/gdb/target.c @@ -1822,8 +1822,9 @@ read_memory_robust (struct target_ops *ops, /* Got an error reading full chunk. See if maybe we can read some subrange. */ xfree (buffer); - read_whatever_is_readable (ops, offset + xfered_total, unit_size, - offset + xfered_total + to_read, &result); + read_whatever_is_readable (ops, offset + xfered_total, + offset + xfered_total + to_read, + unit_size, &result); xfered_total += to_read; } else