[PATCH] objtool: fix .cold. functions parent symbols search

Artem Savkov
2018-11-07T14:06:10Z

The way it is currently done it is possible for read_symbols() to find the
same symbol as parent for ".cold" functions. This leads to a bunch of
complications such as func length being set to 0 and a segfault in
add_switch_table(). Fix by copying the search string instead of modifying
it in place.

Signed-off-by: Artem Savkov <asavkov@redhat.com>
---
tools/objtool/elf.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 6dbb9fae0f9d..781c8afb29b9 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -298,6 +298,7 @@ static int read_symbols(struct elf *elf)
/* Create parent/child links for any cold subfunctions */
list_for_each_entry(sec, &elf->sections, list) {
list_for_each_entry(sym, &sec->symbol_list, list) {
+ char *pname;
if (sym->type != STT_FUNC)
continue;
sym->pfunc = sym->cfunc = sym;
@@ -305,9 +306,9 @@ static int read_symbols(struct elf *elf)
if (!coldstr)
continue;

- coldstr[0] = '\0';
- pfunc = find_symbol_by_name(elf, sym->name);
- coldstr[0] = '.';
+ pname = strndup(sym->name, coldstr - sym->name);
+ pfunc = find_symbol_by_name(elf, pname);
+ free(pname);

if (!pfunc) {
WARN("%s(): can't find parent function",
--
2.17.2