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authorTom de Vries <tdevries@suse.de>2022-07-21 13:05:39 +0200
committerTom de Vries <tdevries@suse.de>2022-07-21 13:05:39 +0200
commit2fe9a3c41faa71b1f2bde40e818187491a5a9925 (patch)
tree2aeb9718f70f0e8412d8703857a3c1e8e664e99e
parentea09fe92596fbb2a5da4595459bfe8b23789ec8d (diff)
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[gdb/symtab] Fix bad compile unit index complaint
I noticed this code in dw2_debug_names_iterator::next: ... case DW_IDX_compile_unit: /* Don't crash on bad data. */ if (ull >= per_bfd->all_comp_units.size ()) { complaint (_(".debug_names entry has bad CU index %s" " [in module %s]"), pulongest (ull), objfile_name (objfile)); continue; } per_cu = per_bfd->get_cu (ull); break; ... This code used to DTRT, before we started keeping both CUs and TUs in all_comp_units. Fix by using "per_bfd->all_comp_units.size () - per_bfd->tu_stats.nr_tus" instead. It's hard to produce a test-case for this, but let's try at least to trigger the complaint somehow. We start out by creating an exec with .debug_types and .debug_names: ... $ gcc -g ~/hello.c -fdebug-types-section $ gdb-add-index -dwarf-5 a.out ... and verify that we don't see any complaints: ... $ gdb -q -batch -iex "set complaints 100" ./a.out ... We look at the CU and TU table using readelf -w and conclude that we have nr_cus == 6 and nr_tus == 1. Now override ull in dw2_debug_names_iterator::next for the DW_IDX_compile_unit case to 6, and we have: ... $ gdb -q -batch -iex "set complaints 100" ./a.out During symbol reading: .debug_names entry has bad CU index 6 [in module a.out] ... After this, it still crashes because this code in dw2_debug_names_iterator::next: ... /* Skip if already read in. */ if (m_per_objfile->symtab_set_p (per_cu)) goto again; ... is called with per_cu == nullptr. Fix this by skipping the entry if per_cu == nullptr. Now revert the fix and observe that the complaint disappears, so we've confirmed that the fix is required. A somewhat similar issue for .gdb_index in dw2_symtab_iter_next has been filed as PR29367. Tested on x86_64-linux, with native and target board cc-with-debug-names. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29336
-rw-r--r--gdb/dwarf2/read.c26
1 files changed, 17 insertions, 9 deletions
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index bcd0110..4223060 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -4970,15 +4970,19 @@ dw2_debug_names_iterator::next ()
switch (attr.dw_idx)
{
case DW_IDX_compile_unit:
- /* Don't crash on bad data. */
- if (ull >= per_bfd->all_comp_units.size ())
- {
- complaint (_(".debug_names entry has bad CU index %s"
- " [in module %s]"),
- pulongest (ull),
- objfile_name (objfile));
- continue;
- }
+ {
+ /* Don't crash on bad data. */
+ int nr_cus = (per_bfd->all_comp_units.size ()
+ - per_bfd->tu_stats.nr_tus);
+ if (ull >= nr_cus)
+ {
+ complaint (_(".debug_names entry has bad CU index %s"
+ " [in module %s]"),
+ pulongest (ull),
+ objfile_name (objfile));
+ continue;
+ }
+ }
per_cu = per_bfd->get_cu (ull);
break;
case DW_IDX_type_unit:
@@ -5016,6 +5020,10 @@ dw2_debug_names_iterator::next ()
}
}
+ /* Skip if we couldn't find a valid CU/TU index. */
+ if (per_cu == nullptr)
+ goto again;
+
/* Skip if already read in. */
if (m_per_objfile->symtab_set_p (per_cu))
goto again;