From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id C5FA7385840C; Tue, 31 Aug 2021 11:51:02 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org C5FA7385840C From: "egb.atos at gmail dot com" To: elfutils-devel@sourceware.org Subject: [Bug libdw/28294] New: dwarf_aggregate_size fails on some array types Date: Tue, 31 Aug 2021 11:51:02 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: elfutils X-Bugzilla-Component: libdw X-Bugzilla-Version: unspecified X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: egb.atos at gmail dot com X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at sourceware dot org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status bug_severity priority component assigned_to reporter cc target_milestone Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: elfutils-devel@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Elfutils-devel mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 31 Aug 2021 11:51:02 -0000 https://sourceware.org/bugzilla/show_bug.cgi?id=3D28294 Bug ID: 28294 Summary: dwarf_aggregate_size fails on some array types Product: elfutils Version: unspecified Status: UNCONFIRMED Severity: normal Priority: P2 Component: libdw Assignee: unassigned at sourceware dot org Reporter: egb.atos at gmail dot com CC: elfutils-devel at sourceware dot org Target Milestone: --- In dwarf_aggregate_size.c, the helper function array_size unconditionally u= ses dwarf_formsdata to obtain the value of the DW_AT_upper_bound attribute for array types. In many cases, this will return a negative value for C arrays that have positive upper bounds, causing the function to return a failure value, which propagates up through dwarf_aggregate_size. This is an exemplary type (via readelf -w): <1><90e>: Abbrev Number: 37 (DW_TAG_array_type) <90f> DW_AT_type : <0x118> <2><913>: Abbrev Number: 11 (DW_TAG_subrange_type) <914> DW_AT_type : <0x2c> <918> DW_AT_upper_bound : 249 And the same type, via eu-readelf --debug-dump=3Dinfo: [ 90e] array_type abbrev: 37 type (ref4) [ 118] [ 913] subrange_type abbrev: 11 type (ref4) [ 2c] upper_bound (data1) 249 If dwarf_aggregate_size is called on this type, when it gets the upper_bound attribute, it will get a value of -7, and fail. For other array sizes, this will work. Looking around a bit, the closest discussion I could find on the topic was = this one about signed vs unsigned interpretation of array bounds back in 2005: http://www.dwarfstd.org/ShowIssue.php?issue=3D020702.1 I exchanged emails with Mark Wielaard on this, and he indicated that this d= id appear to be a bug, but he wasn't sure yet where the correct fix would be. I've tried this with a RISCV compiler (version 8.3.0), an ARM compiler (ver= sion 7.3.1) and an x86 gcc (version 7.5.0). I've not tried it with later versio= ns. Here's the sample code I compiled to get the output above. The output in t= he report is from the ARM compiler. #include int foofunc(int v, char *s) { char buff[250]; strcpy(buff, s); return buff[v]; } int main() { return foofunc(4, "fdjkfd"); } --=20 You are receiving this mail because: You are on the CC list for the bug.=