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v1.4.1 sourceware.org 2ECF3385829F Received: from simark.ca (simark.ca [158.69.221.121]) (authenticated bits=0) by smtp.polymtl.ca (8.14.7/8.14.7) with ESMTP id 26S2XVVu013631 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 27 Jul 2022 22:33:36 -0400 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp.polymtl.ca 26S2XVVu013631 Received: from [10.0.0.11] (192-222-157-6.qc.cable.ebox.net [192.222.157.6]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPSA id 450091E5EA; Wed, 27 Jul 2022 22:33:31 -0400 (EDT) Message-ID: <44c3abd4-0386-da7e-60c2-3fd89458e75f@polymtl.ca> Date: Wed, 27 Jul 2022 22:33:30 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v2] gdb: call check_typedef at beginning of dwarf_expr_context::fetch_result Content-Language: en-US To: Simon Marchi , gdb-patches@sourceware.org References: <20220728013422.2561677-1-simon.marchi@efficios.com> In-Reply-To: <20220728013422.2561677-1-simon.marchi@efficios.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Poly-FromMTA: (simark.ca [158.69.221.121]) at Thu, 28 Jul 2022 02:33:31 +0000 X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Simon Marchi via Gdb-patches Reply-To: Simon Marchi Errors-To: gdb-patches-bounces+public-inbox=simark.ca@sourceware.org Sender: "Gdb-patches" On 2022-07-27 21:34, Simon Marchi wrote: > From: Simon Marchi > > Bug 29374 shows this crash: > > $ ./gdb -nx --data-directory=data-directory -q -batch -ex "catch throw" -ex r -ex bt a.out > ... > /home/simark/src/binutils-gdb/gdb/../gdbsupport/array-view.h:217: internal-error: copy: Assertion `dest.size () == src.size ()' failed. > > The backtrace is: > > #0 internal_error (file=0x5555606504c0 "/home/simark/src/binutils-gdb/gdb/../gdbsupport/array-view.h", line=217, fmt=0x55556064b700 "%s: Assertion `%s' failed.") at /home/simark/src/binutils-gdb/gdbsupport/errors.cc:51 > #1 0x000055555d41c0bb in gdb::copy (src=..., dest=...) at /home/simark/src/binutils-gdb/gdb/../gdbsupport/array-view.h:217 > #2 0x000055555deef28c in dwarf_expr_context::fetch_result (this=0x7fffffffb830, type=0x621007a86830, subobj_type=0x621007a86830, subobj_offset=0, as_lval=false) at /home/simark/src/binutils-gdb/gdb/dwarf2/expr.c:1040 > #3 0x000055555def0015 in dwarf_expr_context::evaluate (this=0x7fffffffb830, addr=0x62f00004313e "0", len=1, as_lval=false, per_cu=0x60b000069550, frame=0x621007c9e910, addr_info=0x0, type=0x621007a86830, subobj_type=0x621007a86830, subobj_offset=0) at /home/simark/src/binutils-gdb/gdb/dwarf2/expr.c:1091 > #4 0x000055555e084327 in dwarf2_evaluate_loc_desc_full (type=0x621007a86830, frame=0x621007c9e910, data=0x62f00004313e "0", size=1, per_cu=0x60b000069550, per_objfile=0x613000006080, subobj_type=0x621007a86830, subobj_byte_offset=0, as_lval=false) at /home/simark/src/binutils-gdb/gdb/dwarf2/loc.c:1485 > #5 0x000055555e0849e2 in dwarf2_evaluate_loc_desc (type=0x621007a86830, frame=0x621007c9e910, data=0x62f00004313e "0", size=1, per_cu=0x60b000069550, per_objfile=0x613000006080, as_lval=false) at /home/simark/src/binutils-gdb/gdb/dwarf2/loc.c:1529 > #6 0x000055555e0828c6 in dwarf_entry_parameter_to_value (parameter=0x621007a96e58, deref_size=0x0, type=0x621007a86830, caller_frame=0x621007c9e910, per_cu=0x60b000069550, per_objfile=0x613000006080) at /home/simark/src/binutils-gdb/gdb/dwarf2/loc.c:1235 > #7 0x000055555e082f55 in value_of_dwarf_reg_entry (type=0x621007a86890, frame=0x621007acc510, kind=CALL_SITE_PARAMETER_DWARF_REG, kind_u=...) at /home/simark/src/binutils-gdb/gdb/dwarf2/loc.c:1332 > #8 0x000055555e083449 in value_of_dwarf_block_entry (type=0x621007a86890, frame=0x621007acc510, block=0x61e000033568 "T\004\205\001\240\004\004\243\001T\237\004\240\004\261\004\001T\004\261\004\304\005\004\243\001T\237\004\304\005\310\005\001T\004\310\005\311\005\004\243\001T\237", block_len=1) at /home/simark/src/binutils-gdb/gdb/dwarf2/loc.c:1365 > #9 0x000055555e094d40 in loclist_read_variable_at_entry (symbol=0x621007a99bd0, frame=0x621007acc510) at /home/simark/src/binutils-gdb/gdb/dwarf2/loc.c:3889 > #10 0x000055555f5192e0 in read_frame_arg (fp_opts=..., sym=0x621007a99bd0, frame=0x621007acc510, argp=0x7fffffffbf20, entryargp=0x7fffffffbf60) at /home/simark/src/binutils-gdb/gdb/stack.c:559 > #11 0x000055555f51c352 in print_frame_args (fp_opts=..., func=0x621007a99ad0, frame=0x621007acc510, num=-1, stream=0x6030000bad90) at /home/simark/src/binutils-gdb/gdb/stack.c:887 > #12 0x000055555f521919 in print_frame (fp_opts=..., frame=0x621007acc510, print_level=1, print_what=LOCATION, print_args=1, sal=...) at /home/simark/src/binutils-gdb/gdb/stack.c:1390 > #13 0x000055555f51f22e in print_frame_info (fp_opts=..., frame=0x621007acc510, print_level=1, print_what=LOCATION, print_args=1, set_current_sal=0) at /home/simark/src/binutils-gdb/gdb/stack.c:1116 > #14 0x000055555f526c6d in backtrace_command_1 (fp_opts=..., bt_opts=..., count_exp=0x0, from_tty=0) at /home/simark/src/binutils-gdb/gdb/stack.c:2079 > #15 0x000055555f527ae5 in backtrace_command (arg=0x0, from_tty=0) at /home/simark/src/binutils-gdb/gdb/stack.c:2198 > > The problem is that the type that gets passed down to > dwarf_expr_context::fetch_result (the type of a variable of which we're > trying to read the entry value) is a typedef whose size has never been > computed yet (check_typedef has never been called on it). As we get in > the DWARF_VALUE_STACK case (line 1028 of dwarf2/expr.c), the `len` > variable is therefore set to 0, instead of the actual type length. We > then call allocate_value on subobj_type, which does call check_typedef, > so the length of the typedef gets filled in at that point. We end up > passing to the copy function a source array view of length 0 and a > target array view of length 4, and the assertion fails. > > Fix this by calling check_typedef on both type and subobj_type at the > beginning of fetch_result. > > I tried writing a test for this using the DWARF assembler, but I haven't > succeeded. It's possible that we need to get into this specific code > path (value_of_dwarf_reg_entry and all) to manage to get to > dwarf_expr_context::fetch_result with a typedef type that has never been > resolved. In all my attempts, the typedef would always be resolved > already, so the bug wouldn't show up. > > As a fallback, I made a gdb.dwarf2 test with a compiler-generated .S > file. I don't particularly like those, but I think it's better than no > test. The .cpp source code is the smallest reproducer I am able to make > from the reproducer given in the bug (thanks to Pedro for suggestions > on how to minimize it further than I had). > > Change-Id: I182733ad08e34df40d8bcc47af72c482fabf4900 > Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29374 Sorry, I forgot that I had already sent this patch. So this is effectively the v2 of this one (I fixed the subject accordingly): https://sourceware.org/pipermail/gdb-patches/2022-July/191035.html This new patch has a test. Simon