From: Julien Thierry <jthie...@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 <jthie...@redhat.com>
Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Reviewed-by: Miroslav Benes <mbe...@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com>
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Sasha Levin <sas...@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 5685fe2c7a7d..247fbb5f6a38 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

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