[tip: x86/urgent] objtool: Make BP scratch register warning more robust

[tip-bot2 for Josh Poimboeuf]

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     b296695298d8632d8b703ac25fe70be34a07c0d9
Gitweb:        https://git.kernel.org/tip/b296695298d8632d8b703ac25fe70be34a07c0d9
Author:        Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
AuthorDate:    Wed, 01 Apr 2020 13:23:29 -05:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Tue, 14 Apr 2020 12:24:22 +02:00

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, ID: 1492002
("Dereference after null check").

Fixes: c705cecc8431 ("objtool: Track original function across branches")
Reported-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lkml.kernel.org/r/afc628693a37acd287e843bcc5c0430263d93c74.1585761021.git.jpoimboe@xxxxxxxxxx
---
 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 cb2d299..4b170fd 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2005,8 +2005,8 @@ 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;
 	}