Re: [PATCH] stm class: Fix out of bound access from bitmap allocation

[Sai Prakash Ranjan]

On 4/5/2019 6:44 PM, David Laight wrote:
> From: Sai Prakash Ranjan
> > diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
> > index 93ce3aa740a9..21a5838f6e67 100644
> > --- a/drivers/hwtracing/stm/core.c
> > +++ b/drivers/hwtracing/stm/core.c
> > @@ -168,7 +168,7 @@ static int stp_master_alloc(struct stm_device *stm, unsigned int idx)
> >   	struct stp_master *master;
> >   	size_t size;
> >
> > -	size = ALIGN(stm->data->sw_nchannels, 8) / 8;
> > +	size = ALIGN(stm->data->sw_nchannels, STM_MASTER_SZ) / STM_MASTER_SZ;
>
> I'm not sure that using STP_MASTER_SZ improves readability at all.

I thought it was better to have a macro than directly specifying
sizeof(unsigned long), anyways I can change it.

> Is there something that gives the size of a bitmap for 'n' items?

Not sure if there is something.

Thanks,
Sai

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