From c44b4b9eeb71f5b0b617abf6fd66d1ef0aab6200 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Wed, 29 Oct 2025 12:54:08 -0700 Subject: [PATCH] objtool: Fix skip_alt_group() for non-alternative STAC/CLAC If an insn->alt points to a STAC/CLAC instruction, skip_alt_group() assumes it's part of an alternative ("alt group") as opposed to some other kind of "alt" such as an exception fixup. While that assumption may hold true in the current code base, Linus has an out-of-tree patch which breaks that assumption by replacing the STAC/CLAC alternatives with raw STAC/CLAC instructions. Make skip_alt_group() more robust by making sure it's actually an alt group before continuing. Reported-by: Linus Torvalds Fixes: 2d12c6fb7875 ("objtool: Remove ANNOTATE_IGNORE_ALTERNATIVE from CLAC/STAC") Closes: https://lore.kernel.org/CAHk-=wi6goUT36sR8GE47_P-aVrd5g38=VTRHpktWARbyE-0ow@mail.gmail.com Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Tested-by: Linus Torvalds Link: https://patch.msgid.link/3d22415f7b8e06a64e0873b21f48389290eeaa49.1761767616.git.jpoimboe@kernel.org --- tools/objtool/check.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 620854fdaaf6..9004fbc06769 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -3516,8 +3516,11 @@ static bool skip_alt_group(struct instruction *insn) { struct instruction *alt_insn = insn->alts ? insn->alts->insn : NULL; + if (!insn->alt_group) + return false; + /* ANNOTATE_IGNORE_ALTERNATIVE */ - if (insn->alt_group && insn->alt_group->ignore) + if (insn->alt_group->ignore) return true; /* -- 2.47.3