Blame SOURCES/gdb-rhbz1708192-parse_macro_definition-crash.patch

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From FEDORA_PATCHES Mon Sep 17 00:00:00 2001
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From: Sergio Durigan Junior <sergiodj@redhat.com>
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Date: Fri, 10 May 2019 16:57:26 -0400
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Subject: gdb-rhbz1708192-parse_macro_definition-crash.patch
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;; "Fix" segfault that happens on parse_macro_definition because
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;; debugedit corrupts the .debug_macro section.
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;; Sergio Durigan Junior, RH BZ 1708192.
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Don't crash if dwarf_decode_macro_bytes's 'body' is NULL
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Hi,
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Ref.: https://bugzilla.redhat.com/show_bug.cgi?id=1708192
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      https://bugzilla.redhat.com/show_bug.cgi?id=1708786
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During the Fedora RPM build process, gdb-add-index is invoked to
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extract the DWARF index from the binary, and GDB will segfault because
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dwarf2read.c:parse_definition_macro's 'body' variable is NULL.
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The underlying problem is that Fedora's rpm-build's "debugedit"
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program will silently corrupt .debug_macro strings when a binary is
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compiled with -g3.  This is being taken care of by Mark Wielaard,
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here:
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  https://bugzilla.redhat.com/show_bug.cgi?id=1708786
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However, I still feel it's important to make GDB more resilient
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against invalid DWARF input, so I'm proposing this rather simple patch
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to catch the situation when "body == NULL" (i.e., it's probably been
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corrupted) and issue a complaint.  This is not a real fix to the
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problem, of course, but at least GDB is able to finish without
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segfaulting.
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OK for master?
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gdb/ChangeLog:
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2019-05-15  Sergio Durigan Junior  <sergiodj@redhat.com>
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	Ref.: https://bugzilla.redhat.com/show_bug.cgi?id=1708192
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	* dwarf2read.c (dwarf_decode_macro_bytes): Check whether 'body' is
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	NULL, and complain if that's the case.
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diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
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--- a/gdb/dwarf2read.c
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+++ b/gdb/dwarf2read.c
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@@ -24355,7 +24355,21 @@ dwarf_decode_macro_bytes (struct dwarf2_per_objfile *dwarf2_per_objfile,
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 			 is_define ? _("definition") : _("undefinition"),
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 			 line == 0 ? _("zero") : _("non-zero"), line, body);
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-	    if (is_define)
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+	    if (body == NULL)
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+	      {
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+		/* Fedora's rpm-build's "debugedit" binary
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+		   corrupted .debug_macro sections.
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+
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+		   For more info, see
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+		   https://bugzilla.redhat.com/show_bug.cgi?id=1708786 */
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+		complaint (_("debug info gives %s invalid macro %s "
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+			     "without body (corrupted?) at line %d "
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+			     "on file %s"),
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+			   at_commandline ? _("command-line") : _("in-file"),
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+			   is_define ? _("definition") : _("undefinition"),
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+			   line, current_file->filename);
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+	      }
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+	    else if (is_define)
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 	      parse_macro_definition (current_file, line, body);
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 	    else
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 	      {