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SubjectRe: [PATCH] objtool: check: Fix NULL pointer dereference
On Mon, Mar 30, 2020 at 07:20:40PM -0500, Gustavo A. R. Silva wrote:
> 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@embeddedor.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;

We should still do the warning even if there's no func. I'll make a
slightly different patch which unconditionally uses WARN_FUNC().

I'll give you Reported-by credit and keep the coverity tag. Thanks!

--
Josh

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