linux-kernel - [PATCH] objtool: check: Fix NULL pointer dereference

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Message-ID: <20200331002040.GA11302@embeddedor>
Date:   Mon, 30 Mar 2020 19:20:40 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH] objtool: check: Fix NULL pointer dereference

In case func is null, there is a null pointer dereference at 2029:

2029                 WARN("%s uses BP as a scratch register",
2030                      func->name);

Fix this by null-checking func.

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

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index e3bb76358148..182cc48fa892 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2025,7 +2025,7 @@ static int validate_return(struct symbol *func, struct instruction *insn, struct
 		return 1;
 	}
 
-	if (state->bp_scratch) {
+	if (func && state->bp_scratch) {
 		WARN("%s uses BP as a scratch register",
 		     func->name);
 		return 1;
-- 
2.26.0