I just tripped over a segfault in libbacktrace. We apply strrchr to a
possibly NULL filename, with predictable results when it is.
elf.c:3044 passes NULL as the filename parm:
ret = elf_add (state, NULL, d, base_address, error_callback, data,
fileline_fn, found_sym, found_dwarf, NULL, 0, 1, NULL,
0);
This gets to elf_open_debugfile_by_debuglink which passes it on through:
ddescriptor = elf_find_debugfile_by_debuglink (state, filename,
debuglink_name,
error_callback, data);
this patch avoids the strrchr when filename is null. I reordered the
way prefix & prefix len got set, finding it prefereable to:
slash = filename ? NULL : strrchr (filename, '/');
but if you prefer to avoid the assignment in the conditional I'm fine
with that too.
ok?
nathan
--
Nathan Sidwell
2019-01-24 Nathan Sidwell <nat...@acm.org>
* elf.c (elf_find_debugfile_by_debuglink): Protect against
FILENAME being NULL.
Index: libbacktrace/elf.c
===================================================================
--- libbacktrace/elf.c (revision 268252)
+++ libbacktrace/elf.c (working copy)
@@ -970,13 +970,9 @@ elf_find_debugfile_by_debuglink (struct
/* Look for DEBUGLINK_NAME in the same directory as FILENAME. */
- slash = strrchr (filename, '/');
- if (slash == NULL)
- {
- prefix = "";
- prefix_len = 0;
- }
- else
+ prefix = "";
+ prefix_len = 0;
+ if (filename && (slash = strrchr (filename, '/') != NULL)
{
slash++;
prefix = filename;
