From a4cd947aca23d58966ead843e120f4c19db01030 Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Tue, 11 Sep 2018 23:50:15 +0930 Subject: [PATCH] PR23425, unresolved symbol diagnostic dwarf2.c code reasonably assumes that debug info is local to a file, an assumption now violated by gcc, resulting in "DWARF error: invalid abstract instance DIE ref" or wrong details when attempting to print linker error messages with file, function and line reported. This is because find_abstract_instance is only prepared to handle DW_FORM_ref_addr when the .debug_info section referenced is in the current file. When that isn't the case, relocations to access another file's .debug_info will typically be against a symbol defined at the start of that .debug_info section, plus an addend. Since the dwarf2.c code only considers the current file's debug info, that symbol will be undefined, resolving to zero. In effect the ref_addr will wrongly resolve to the current file's .debug_info. This patch avoids the problem by treating relocations in debug sections against undefined symbols in a similar manner to the way relocations against symbols defined in discarded sections are resolved. They result in a zero value (except in .debug_ranges) regardless of the addend. PR 23425 * reloc.c (bfd_generic_get_relocated_section_contents): Zero reloc fields in debug sections when reloc is against an undefined symbol and called from bfd_simple_get_relocated_section_contents or similar. * dwarf2.c (find_abstract_instance): Return true for zero offset DW_FORM_ref_addr without returning values. --- bfd/ChangeLog | 10 ++++++++++ bfd/dwarf2.c | 4 +++- bfd/reloc.c | 13 ++++++++++++- 3 files changed, 25 insertions(+), 2 deletions(-) diff --git a/bfd/ChangeLog b/bfd/ChangeLog index a4991050cd8..bbc8e9f352f 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,3 +1,13 @@ +2018-09-14 Alan Modra + + PR 23425 + * reloc.c (bfd_generic_get_relocated_section_contents): Zero reloc + fields in debug sections when reloc is against an undefined symbol + and called from bfd_simple_get_relocated_section_contents or + similar. + * dwarf2.c (find_abstract_instance): Return true for zero offset + DW_FORM_ref_addr without returning values. + 2018-09-06 Alan Modra PR 23570 diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c index 8fadb5c4b62..3b2885599ea 100644 --- a/bfd/dwarf2.c +++ b/bfd/dwarf2.c @@ -2837,7 +2837,9 @@ find_abstract_instance (struct comp_unit * unit, info_ptr = unit->stash->info_ptr_memory; info_ptr_end = unit->stash->info_ptr_end; total = info_ptr_end - info_ptr; - if (!die_ref || die_ref >= total) + if (!die_ref) + return TRUE; + else if (die_ref >= total) { _bfd_error_handler (_("DWARF error: invalid abstract instance DIE ref")); diff --git a/bfd/reloc.c b/bfd/reloc.c index eba60918912..67457418e6e 100644 --- a/bfd/reloc.c +++ b/bfd/reloc.c @@ -8259,7 +8259,18 @@ bfd_generic_get_relocated_section_contents (bfd *abfd, goto error_return; } - if (symbol->section && discarded_section (symbol->section)) + /* Zap reloc field when the symbol is from a discarded + section, ignoring any addend. Do the same when called + from bfd_simple_get_relocated_section_contents for + undefined symbols in debug sections. This is to keep + debug info reasonably sane, in particular so that + DW_FORM_ref_addr to another file's .debug_info isn't + confused with an offset into the current file's + .debug_info. */ + if ((symbol->section != NULL && discarded_section (symbol->section)) + || (symbol->section == bfd_und_section_ptr + && (input_section->flags & SEC_DEBUGGING) != 0 + && link_info->input_bfds == link_info->output_bfd)) { bfd_byte *p; static reloc_howto_type none_howto -- 2.30.2