[PATCH AUTOSEL 4.9 04/50] objtool: Ignore empty alternatives

Sasha Levin
2020-06-08T23:33:08Z

From: Julien Thierry <jthierry@redhat.com>

[ Upstream commit 7170cf47d16f1ba29eca07fd818870b7af0a93a5 ]

The .alternatives section can contain entries with no original
instructions. Objtool will currently crash when handling such an entry.

Just skip that entry, but still give a warning to discourage useless
entries.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/objtool/check.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index b0b8ba9b800c..c7399d7f4bc7 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -778,6 +778,12 @@ static int add_special_section_alts(struct objtool_file *file)
}

if (special_alt->group) {
+ if (!special_alt->orig_len) {
+ WARN_FUNC("empty alternative entry",
+ orig_insn->sec, orig_insn->offset);
+ continue;
+ }
+
ret = handle_group_alt(file, special_alt, orig_insn,
&new_insn);
if (ret)
--
2.25.1