Re: [PATCH] scsi: mpt3sas: FIx a NULL pointer dereference bug in mpt3sas_transport_port_add()

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Jan 25, 2022 at 01:21:20AM +0800, Zhou Qingyang wrote:
> In mpt3sas_transport_port_add(), sas_end_device_alloc() is assigned to rphy
> and there is a dereference of it. sas_end_device_alloc() could return NULL
> on failure of allocation, which could introduce a NULL pointer dereference
> bug.
> 
> The same as sas_expander_alloc().
> 
> Fix this bug by adding a NULL check of rphy.
> 
> This bug was found by a static analyzer.
> 
> Builds with 'make allyesconfig' show no new warnings,
> and our static analyzer no longer warns about this code.
> 
> Fixes: f92363d12359 ("mpt3sas: add new driver supporting 12GB SAS")
> Signed-off-by: Zhou Qingyang <zhou1615@umn.edu>
> ---
> The analysis employs differential checking to identify inconsistent 
> security operations (e.g., checks or kfrees) between two code paths 
> and confirms that the inconsistent operations are not recovered in the
> current function or the callers, so they constitute bugs. 
> 
> Note that, as a bug found by static analysis, it can be a false
> positive or hard to trigger. Multiple researchers have cross-reviewed
> the bug.
> 
>  drivers/scsi/mpt3sas/mpt3sas_transport.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/scsi/mpt3sas/mpt3sas_transport.c b/drivers/scsi/mpt3sas/mpt3sas_transport.c
> index 0681daee6c14..1caa929cf8bc 100644
> --- a/drivers/scsi/mpt3sas/mpt3sas_transport.c
> +++ b/drivers/scsi/mpt3sas/mpt3sas_transport.c
> @@ -823,6 +823,11 @@ mpt3sas_transport_port_add(struct MPT3SAS_ADAPTER *ioc, u16 handle,
>  			hba_port->sas_address =
>  			    mpt3sas_port->remote_identify.sas_address;
>  	}
> +	if (!rphy) {
> +		ioc_err(ioc, "failure at %s:%d/%s()!\n",
> +			__FILE__, __LINE__, __func__);
> +		goto out_fail;
> +	}
>  
>  	rphy->identify = mpt3sas_port->remote_identify;
>  
> -- 
> 2.25.1
> 

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