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gdb: Fix out of bounds array access in buildsym_compunit::record_line 

This commit:

  commit 8c95582da8
  Date:   Mon Dec 30 21:04:51 2019 +0000

      gdb: Add support for tracking the DWARF line table is-stmt field

Introduced an invalid memory access, by reading outside the bounds of
an array.

This would cause this valgrind error:

  ==7633== Invalid read of size 4
  ==7633==    at 0x4D002C: buildsym_compunit::record_line(subfile*, int, unsigned long, bool) (buildsym.c:688)
  ==7633==    by 0x5F60A5: dwarf_record_line_1(gdbarch*, subfile*, unsigned int, unsigned long, bool, dwarf2_cu*) (read.c:19956)
  ==7633==    by 0x5F63B0: lnp_state_machine::record_line(bool) (read.c:20024)
  ==7633==    by 0x5F5DD5: lnp_state_machine::handle_special_opcode(unsigned char) (read.c:19851)
  ==7633==    by 0x5F6706: dwarf_decode_lines_1(line_header*, dwarf2_cu*, int, unsigned long) (read.c:20135)
  ==7633==    by 0x5F6C57: dwarf_decode_lines(line_header*, char const*, dwarf2_cu*, dwarf2_psymtab*, unsigned long, int) (read.c:20328)
  ==7633==    by 0x5DF5F1: handle_DW_AT_stmt_list(die_info*, dwarf2_cu*, char const*, unsigned long) (read.c:10748)
  ==7633==    by 0x5DF823: read_file_scope(die_info*, dwarf2_cu*) (read.c:10796)
  ==7633==    by 0x5DDA63: process_die(die_info*, dwarf2_cu*) (read.c:9815)
  ==7633==    by 0x5DD44A: process_full_comp_unit(dwarf2_per_cu_data*, language) (read.c:9580)
  ==7633==    by 0x5DAB58: process_queue(dwarf2_per_objfile*) (read.c:8867)
  ==7633==    by 0x5CB30E: dw2_do_instantiate_symtab(dwarf2_per_cu_data*, bool) (read.c:2374)
  ==7633==  Address 0xa467f48 is 8 bytes before a block of size 16,024 alloc'd
  ==7633==    at 0x4C2CDCB: malloc (vg_replace_malloc.c:299)
  ==7633==    by 0x451FC4: xmalloc (alloc.c:60)
  ==7633==    by 0x4CFFDF: buildsym_compunit::record_line(subfile*, int, unsigned long, bool) (buildsym.c:678)
  ==7633==    by 0x5F60A5: dwarf_record_line_1(gdbarch*, subfile*, unsigned int, unsigned long, bool, dwarf2_cu*) (read.c:19956)
  ==7633==    by 0x5F63B0: lnp_state_machine::record_line(bool) (read.c:20024)
  ==7633==    by 0x5F5DD5: lnp_state_machine::handle_special_opcode(unsigned char) (read.c:19851)
  ==7633==    by 0x5F6706: dwarf_decode_lines_1(line_header*, dwarf2_cu*, int, unsigned long) (read.c:20135)
  ==7633==    by 0x5F6C57: dwarf_decode_lines(line_header*, char const*, dwarf2_cu*, dwarf2_psymtab*, unsigned long, int) (read.c:20328)
  ==7633==    by 0x5DF5F1: handle_DW_AT_stmt_list(die_info*, dwarf2_cu*, char const*, unsigned long) (read.c:10748)
  ==7633==    by 0x5DF823: read_file_scope(die_info*, dwarf2_cu*) (read.c:10796)
  ==7633==    by 0x5DDA63: process_die(die_info*, dwarf2_cu*) (read.c:9815)
  ==7633==    by 0x5DD44A: process_full_comp_unit(dwarf2_per_cu_data*, language) (read.c:9580)

gdb/ChangeLog:

	* buildsyms.c (buildsym_compunit::record_line): Avoid accessing
	previous item in the list, when the list has no items.
This commit is contained in:
Andrew Burgess 2020-03-11 11:17:39 +00:00
parent 5496f3c635
commit dcc050c86c
2 changed files with 16 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
gdb/ChangeLog
View File

@ -1,3 +1,8 @@
2020-03-11 Andrew Burgess <andrew.burgess@embecosm.com>
* buildsyms.c (buildsym_compunit::record_line): Avoid accessing
previous item in the list, when the list has no items.
2020-03-11 Tom de Vries <tdevries@suse.de>
* dwarf2/loc.c (dwarf2_evaluate_property): Handle NULL frame in

19
gdb/buildsym.c
View File

@ -681,15 +681,18 @@ buildsym_compunit::record_line (struct subfile *subfile, int line,
m_have_line_numbers = true;
}
/* If we have a duplicate for the previous entry then ignore the new
entry, except, if the new entry is setting the is_stmt flag, then
ensure the previous entry respects the new setting. */
e = subfile->line_vector->item + subfile->line_vector->nitems - 1;
if (e->line == line && e->pc == pc)
if (subfile->line_vector->nitems > 0)
{
if (is_stmt && !e->is_stmt)
e->is_stmt = 1;
return;
/* If we have a duplicate for the previous entry then ignore the new
entry, except, if the new entry is setting the is_stmt flag, then
ensure the previous entry respects the new setting. */
e = subfile->line_vector->item + subfile->line_vector->nitems - 1;
if (e->line == line && e->pc == pc)
{
if (is_stmt && !e->is_stmt)
e->is_stmt = 1;
return;
}
}
if (subfile->line_vector->nitems + 1 >= subfile->line_vector_length)