linux-kernel - [PATCH 5/5] objtool: Make BP scratch register warning more robust

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Message-Id: <afc628693a37acd287e843bcc5c0430263d93c74.1585761021.git.jpoimboe@redhat.com>
Date:   Wed,  1 Apr 2020 13:23:29 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Julien Thierry <jthierry@...hat.com>,
        "Gustavo A . R . Silva" <gustavo@...eddedor.com>
Subject: [PATCH 5/5] objtool: Make BP scratch register warning more robust

If func is NULL, a seg fault can result.

This is a theoretical issue which was found by Coverity.

Fixes: c705cecc8431 ("objtool: Track original function across branches")
Addresses-Coverity-ID: 1492002 ("Dereference after null check")
Reported-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 tools/objtool/check.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index c681a26c25ac..93fa7be67e9f 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2023,8 +2023,8 @@ static int validate_return(struct symbol *func, struct instruction *insn, struct
 	}
 
 	if (state->bp_scratch) {
-		WARN("%s uses BP as a scratch register",
-		     func->name);
+		WARN_FUNC("BP used as a scratch register",
+			  insn->sec, insn->offset);
 		return 1;
 	}
 
-- 
2.21.1