linux-kernel - Re: [PATCH] objtool: Fix calloc call for new -Walloc-size

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Date:   Fri, 17 Nov 2023 10:30:52 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...nel.org>
Cc:     Sam James <sam@...too.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] objtool: Fix calloc call for new -Walloc-size

On Thu, Nov 09, 2023 at 01:40:30PM -0800, Josh Poimboeuf wrote:
> On Tue, Nov 07, 2023 at 08:55:00PM +0000, Sam James wrote:
> > GCC 14 introduces a new -Walloc-size included in -Wextra which errors out
> > like:
> > ```
> > check.c: In function ‘cfi_alloc’:
> > check.c:294:33: error: allocation of insufficient size ‘1’ for type ‘struct cfi_state’ with size ‘320’ [-Werror=alloc-size]
> >   294 |         struct cfi_state *cfi = calloc(sizeof(struct cfi_state), 1);
> >       |                                 ^~~~~~
> > ```
> > 
> > The calloc prototype is:
> > ```
> > void *calloc(size_t nmemb, size_t size);
> > ```
> > 
> > So, just swap the number of members and size arguments to match the prototype, as
> > we're initialising 1 struct of size `sizeof(struct ...)`. GCC then sees we're not
> > doing anything wrong.
> > 
> > Signed-off-by: Sam James <sam@...too.org>
> > ---
> >  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 e94756e09ca9..548ec3cd7c00 100644
> > --- a/tools/objtool/check.c
> > +++ b/tools/objtool/check.c
> > @@ -291,7 +291,7 @@ static void init_insn_state(struct objtool_file *file, struct insn_state *state,
> >  
> >  static struct cfi_state *cfi_alloc(void)
> >  {
> > -	struct cfi_state *cfi = calloc(sizeof(struct cfi_state), 1);
> > +	struct cfi_state *cfi = calloc(1, sizeof(struct cfi_state));
> >  	if (!cfi) {
> >  		WARN("calloc failed");
> >  		exit(1);
> 
> Thanks!
> 
> Acked-by: Josh Poimboeuf <jpoimboe@...nel.org>
> 
> Peter are you able to grab this or should I put it in my tree first?

Got it, thanks!