linux-kernel - Re: [PATCH 3/3] scsi: storvsc: Validate length of incoming packet in storvsc_on_channel

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Date:   Tue, 30 Mar 2021 11:08:15 +0200
From:   Andrea Parri <parri.andrea@...il.com>
To:     Olaf Hering <olaf@...fle.de>
Cc:     linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org,
        "K . Y . Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Saruhan Karademir <skarade@...rosoft.com>,
        Juan Vazquez <juvazq@...rosoft.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org
Subject: Re: [PATCH 3/3] scsi: storvsc: Validate length of incoming packet in
 storvsc_on_channel_callback()

Hi Olaf,

On Mon, Mar 29, 2021 at 06:37:21PM +0200, Olaf Hering wrote:
> On Thu, Dec 17, Andrea Parri (Microsoft) wrote:
> 
> > Check that the packet is of the expected size at least, don't copy data
> > past the packet.
> 
> > +		if (hv_pkt_datalen(desc) < sizeof(struct vstor_packet) -
> > +				stor_device->vmscsi_size_delta) {
> > +			dev_err(&device->device, "Invalid packet len\n");
> > +			continue;
> > +		}
> > +
> 
> Sorry for being late:
> 
> It might be just cosmetic, but should this check be done prior the call to vmbus_request_addr()?

TBH, I'm not immediately seeing why it 'should'; it could make sense to move
the check on the packet data length.


> Unrelated: my copy of vmbus_request_addr() can return 0, which is apparently not handled by this loop in storvsc_on_channel_callback().

Indeed, IDs of 0 are reserved for so called unsolicited messages; I think we
should check that storvsc_on_io_completion() is not called on such messages.

Thanks,
  Andrea