From 1c04f72368c925288a6f1b1abb0dbc31a60d2f49 Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Tue, 30 Aug 2022 10:22:28 +0200 Subject: [gdb/symtab] Fix assert in set_length When running the included test-case, we run into: ... (gdb) break _start^M read.h:309: internal-error: set_length: \ Assertion `m_length == length' failed.^M ... The problem is that while there are two CUs: ... $ readelf -wi debug-names-missing-cu | grep @ Compilation Unit @ offset 0x0: Compilation Unit @ offset 0x2d: ... the CU table in the .debug_names section only contains the first one: ... CU table: [ 0] 0x0 ... The incomplete CU table makes create_cus_from_debug_names_list set the size of the CU at 0x0 to the actual size of both CUs combined. This eventually leads to the assert, when we read the actual size from the CU header. While having an incomplete CU table in a .debug_names section is incorrect, we need a better failure mode than asserting. The easiest way to fix this is to set the length to 0 (meaning: unkown) in create_cus_from_debug_names_list. This makes the failure mode to accept the incomplete CU table, but to ignore the missing CU. It would be nice to instead reject the .debug_names index, and build a complete CU list, but the point where we find this out is well after dwarf2_initialize_objfile, so it looks rather intrusive to restart at that point. Tested on x86_64-linux. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29453 --- gdb/dwarf2/read.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'gdb/dwarf2') diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index 84faeb4..6c6ca96 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -4655,7 +4655,9 @@ create_cus_from_debug_names_list (dwarf2_per_bfd *per_bfd, " ignoring .debug_names.")); return false; } - const ULONGEST length = sect_off_next - sect_off_prev; + /* Note: we're not using length = sect_off_next - sect_off_prev, + to gracefully handle an incomplete CU list. */ + const ULONGEST length = 0; dwarf2_per_cu_data_up per_cu = create_cu_from_index_list (per_bfd, §ion, is_dwz, sect_off_prev, length); -- cgit v1.1