Re: [PATCH 10/16] scsi: arcmsr: Buffer overflow in arcmsr_iop_message_xfer()

[Greg KH <greg@kroah.com>]

On Wed, Dec 14, 2016 at 01:24:52PM +0100, Philipp Hahn wrote:
> From: Dan Carpenter <dan.carpenter@oracle.com>
> 
> [ Upstream commit 7bc2b55a5c030685b399bb65b6baa9ccc3d1f167 ]
> 
> We need to put an upper bound on "user_len" so the memcpy() doesn't
> overflow.
> 
> References: CVE-2016-7425
> Cc: <stable@vger.kernel.org>
> Reported-by: Marco Grassi <marco.gra@gmail.com>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> Reviewed-by: Tomas Henzl <thenzl@redhat.com>
> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
> Signed-off-by: Philipp Hahn <hahn@univention.de>
> ---
>  drivers/scsi/arcmsr/arcmsr_hba.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/arcmsr/arcmsr_hba.c b/drivers/scsi/arcmsr/arcmsr_hba.c
> index 2926295..c9f87cd 100644
> --- a/drivers/scsi/arcmsr/arcmsr_hba.c
> +++ b/drivers/scsi/arcmsr/arcmsr_hba.c
> @@ -2300,7 +2300,8 @@ static int arcmsr_iop_message_xfer(struct AdapterControlBlock *acb,
>  	}
>  	case ARCMSR_MESSAGE_WRITE_WQBUFFER: {
>  		unsigned char *ver_addr;
> -		int32_t user_len, cnt2end;
> +		uint32_t user_len;
> +		int32_t cnt2end;
>  		uint8_t *pQbuffer, *ptmpuserbuffer;
>  		ver_addr = kmalloc(ARCMSR_API_DATA_BUFLEN, GFP_ATOMIC);
>  		if (!ver_addr) {
> @@ -2309,6 +2310,11 @@ static int arcmsr_iop_message_xfer(struct AdapterControlBlock *acb,
>  		}
>  		ptmpuserbuffer = ver_addr;
>  		user_len = pcmdmessagefld->cmdmessage.Length;
> +		if (user_len > ARCMSR_API_DATA_BUFLEN) {
> +			retvalue = ARCMSR_MESSAGE_FAIL;
> +			kfree(ver_addr);
> +			goto message_out;
> +		}
>  		memcpy(ptmpuserbuffer,
>  			pcmdmessagefld->messagedatabuffer, user_len);
>  		spin_lock_irqsave(&acb->wqbuffer_lock, flags);
> -- 
> 2.1.4

I don't understand, what are we supposed to do with this patch?

confused,

greg k-h