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dwarf2_build_psymtabs should check that .debug_line exists
- From: david carlton <carlton at math dot stanford dot edu>
- To: gdb-patches at sources dot redhat dot com
- Cc: carlton at math dot stanford dot edu
- Date: Wed, 7 Aug 2002 16:53:22 -0700
- Subject: dwarf2_build_psymtabs should check that .debug_line exists
I was reading through dwarf2read.c when I noticed that
dwarf2_build_psymtabs() doesn't check to see if the file that you're
debugging has a .debug_line section before initializing
dwarf_line_buffer. This is potentially unfortunate:
dwarf2_build_psymtabs() is called when dwarf2_has_info() returns 1,
but dwarf2_has_info() only checks to see if the file that you're
debugging has .debug_info and .debug_abbrev sections.
It is, of course, quite rare for a file to have .debug_info and
.debug_abbrev sections but not to have a .debug_line section; so,
obviously this isn't a serious problem. And, even if you produce such
a file (using objcopy -R .debug_line, say), it's still pretty hard to
cause GDB to signal an error, but with some effort I did manage to do
so. (I can submit a PR with details, if anybody wants.) Given that
dwarf2_build_psymtabs() is careful to make sure all the other
.debug_XXX sections exist, it should certainly also check to make sure
that .debug_line exists.
By the way, I checked to see where the contents of the .debug_line
section are used; as far as I can tell, it's only used in
dwarf2read.c(dwarf_decode_line_header), and that function does have a
check in it to make sure that dwarf_line_buffer is non-NULL. So this
fix is probably better than the other obvious fix, namely to have
dwarf2_has_info() ensure that the file has a .debug_line section.
Here's a patch; no new regressions.
2002-08-07 David Carlton <carlton@math.stanford.edu>
* dwarf2read.c (dwarf2_build_psymtabs): Check that
dwarf_line_offset is nonzero before creating dwarf_line_buffer.
Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.64
diff -u -p -r1.64 dwarf2read.c
--- dwarf2read.c 31 Jul 2002 22:35:30 -0000 1.64
+++ dwarf2read.c 7 Aug 2002 22:55:49 -0000
@@ -1009,9 +1009,13 @@ dwarf2_build_psymtabs (struct objfile *o
dwarf_abbrev_buffer = dwarf2_read_section (objfile,
dwarf_abbrev_offset,
dwarf_abbrev_size);
- dwarf_line_buffer = dwarf2_read_section (objfile,
- dwarf_line_offset,
- dwarf_line_size);
+
+ if (dwarf_line_offset)
+ dwarf_line_buffer = dwarf2_read_section (objfile,
+ dwarf_line_offset,
+ dwarf_line_size);
+ else
+ dwarf_line_buffer = NULL;
if (dwarf_str_offset)
dwarf_str_buffer = dwarf2_read_section (objfile,
David Carlton
carlton@math.stanford.edu