Re: [PATCH] mpt3sas: Avoid test/set_bit() operating in non-allocated memory

[Keith Busch]

On Fri, May 31, 2024 at 11:00:54AM -0700, Breno Leitao wrote:
> diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c
> index 258647fc6bdd..fe9f4a4175d1 100644
> --- a/drivers/scsi/mpt3sas/mpt3sas_base.c
> +++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
> @@ -8512,6 +8512,12 @@ mpt3sas_base_attach(struct MPT3SAS_ADAPTER *ioc)
>  	ioc->pd_handles_sz = (ioc->facts.MaxDevHandle / 8);
>  	if (ioc->facts.MaxDevHandle % 8)
>  		ioc->pd_handles_sz++;
> +	/* pd_handles_sz should have, at least, the minimal room
> +	 * for set_bit()/test_bit(), otherwise out-of-memory touch
> +	 * may occur
> +	 */
> +	ioc->pd_handles_sz = ALIGN(ioc->pd_handles_sz, sizeof(unsigned long));
> +
>  	ioc->pd_handles = kzalloc(ioc->pd_handles_sz,
>  	    GFP_KERNEL);
>  	if (!ioc->pd_handles) {
> @@ -8529,6 +8535,12 @@ mpt3sas_base_attach(struct MPT3SAS_ADAPTER *ioc)
>  	ioc->pend_os_device_add_sz = (ioc->facts.MaxDevHandle / 8);
>  	if (ioc->facts.MaxDevHandle % 8)
>  		ioc->pend_os_device_add_sz++;
> +
> +	/* pend_os_device_add_sz should have, at least, the minimal room
> +	 * for set_bit()/test_bit(), otherwise out-of-memory may occur
> +	 */
> +	ioc->pend_os_device_add_sz = ALIGN(ioc->pend_os_device_add_sz,
> +					   sizeof(unsigned long));
>  	ioc->pend_os_device_add = kzalloc(ioc->pend_os_device_add_sz,
>  	    GFP_KERNEL);
>  	if (!ioc->pend_os_device_add) {

Do we need similiar ALIGN for _base_check_ioc_facts_changes() too?
Otherwise, yeah, the {test,set,clear}_bit() ops expect an address to
something aligned to 'unsigned long'.