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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] [PATCH] support >2TB SCSI disks
Date: Wed, 28 Jan 2009 12:30:28 +0000
References: <20090127224619.3ae16173@bree.surriel.com>
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To: qemu-devel@nongnu.org

> =A0 =A0 =A0case 0:
> - =A0 =A0 =A0 =A0lba =3D buf[3] | (buf[2] << 8) | ((buf[1] & 0x1f) << 16);
> + =A0 =A0 =A0 =A0lba =3D (uint64_t) buf[3] | ((uint64_t) buf[2] << 8) |
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0(((uint64_t) buf[1] & 0x1f) << 16);

This is not required, though I guess it's harmless.

> =A0 =A0 =A0case 4:
>...
> =A0 =A0 =A0 =A0 =A0len =3D buf[13] | (buf[12] << 8) | (buf[11] << 16) | (=
buf[10] << 24);
>...
> + =A0 =A0case 0x88:
> =A0 =A0 =A0 =A0 =A0r->sector_count =3D len * s->cluster_size;

Implementing these commands introduces several overflows. There are several=
=20
places (including SCSIRequest->sector_count and the return value from=20
scsi_send_comand) that assume the transfer length fits in a signed (32-bit)=
=20
int.

We should to implement the Block Limits VPD page, and enforce these limits.

> + =A0 =A0 =A0 =A0 =A0 =A0/* Returned value is the address of the last sec=
tor. =A0*/
> + =A0 =A0 =A0 =A0 =A0 =A0if (nb_sectors) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0nb_sectors--;

By my reading both this and the current Read Capacity(10)  are incorrect.
They need to divide by s->cluster_size.

Paul