Re: [bug report] firmware: arm_ffa: Add schedule receiver callback mechanism

[Sudeep Holla <sudeep.holla@arm.com>]

On Tue, Oct 31, 2023 at 07:15:45AM +0300, Dan Carpenter wrote:
> On Mon, Oct 30, 2023 at 04:01:07PM +0000, Sudeep Holla wrote:
> > On Mon, Oct 30, 2023 at 05:31:04PM +0300, Dan Carpenter wrote:
> > > Hello Sudeep Holla,
> > > 
> > > The patch 0184450b8b1e: "firmware: arm_ffa: Add schedule receiver
> > > callback mechanism" from Oct 5, 2023 (linux-next), leads to the
> > > following Smatch static checker warning:
> > > 
> > > 	drivers/firmware/arm_ffa/driver.c:1251 ffa_partitions_cleanup()
> > > 	warn: double check that we're allocating correct size: 8 vs 88
> > > 
> > > drivers/firmware/arm_ffa/driver.c
> > >     1243 static void ffa_partitions_cleanup(void)
> > >     1244 {
> > >     1245         struct ffa_dev_part_info **info;
> > >     1246         int idx, count = drv_info->partition_count;
> > >     1247 
> > >     1248         if (!count)
> > >     1249                 return;
> > >     1250 
> > > --> 1251         info = kcalloc(count, sizeof(**info), GFP_KERNEL);
> > > 
> > > I *think* this should be sizeof(*info).  It ends up being a smaller
> > > allocation (8 bytes instead of 88).
> > 
> > Not sure if I am following this warning properly. I am bit confused whether
> > it suggest 8 is correct or 88 is correct. Anyways, the expectation is to
> > just allocate 8 bytes for a pointer. We just fetch a list of stored pointer
> > in XArray and free them.
> > 
> > One possible way to avoid any confusion is to use sizeof(struct ffa_dev_part_info *)
> > or even sizeof(void *).
> 
> The static checker is saying that 8 is correct but we are allocating 88
> bytes.

OK 88 bytes was bit misleading for me initially but then realised that
when all the debug options are enables rwlock_t is 72bytes instead of 8bytes.
I was expecting 24 bytes in place 88 bytes.

> There is an extra * in the sizeof().
>

That said, I was completely blind about this. Sorry for that, clearly a
type that got missed so far.

> I don't necessarily like to make buffers smaller in case I have
> misunderstood the code, but it seems like we should do that here.
>

Agreed, sorry as I said I was confused with the report for other reason
as mentioned above as well as blindness to the typo I have made :D.

I will send a fix soon.

-- 
Regards,
Sudeep

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