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

tip-bot2 for Josh Poimboeuf
2020-04-14T10:56:47Z

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@redhat.com>
AuthorDate: Wed, 01 Apr 2020 13:23:29 -05:00
Committer: Borislav Petkov <bp@suse.de>
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@embeddedor.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/afc628693a37acd287e843bcc5c0430263d93c74.1585761021.git.jpoimboe@redhat.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 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;
}