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[Qemu-devel] [PATCH 1/3] fix signed/unsigned overflows in SCSI disk
From: |
Rik van Riel |
Subject: |
[Qemu-devel] [PATCH 1/3] fix signed/unsigned overflows in SCSI disk |
Date: |
Wed, 28 Jan 2009 09:51:38 -0500 |
User-agent: |
quilt/0.46-1 |
Sector numbers can overflow on a virtual scsi disk of over 1TB
in size. Qemu's bdrv_read expects an int64_t, so fix the overflow
by going to that data type.
On large disks, we clip the capacity to 2TB instead of returning
"capacity modulo 2TB".
Turn sector_count into an unsigned to prevent a signed/unsigned
overflow with SCSI transfers larger than 2TB. We're unlikely to
ever hit this bug, but fixing it is just one line.
Signed-off-by: Rik van Riel <address@hidden>
Index: qemu/trunk/hw/scsi-disk.c
===================================================================
--- qemu.orig/trunk/hw/scsi-disk.c
+++ qemu/trunk/hw/scsi-disk.c
@@ -47,11 +47,11 @@ do { fprintf(stderr, "scsi-disk: " fmt ,
typedef struct SCSIRequest {
SCSIDeviceState *dev;
uint32_t tag;
- /* ??? We should probably keep track of whether the data trasfer is
+ /* ??? We should probably keep track of whether the data transfer is
a read or a write. Currently we rely on the host getting it right. */
/* Both sector and sector_count are in terms of qemu 512 byte blocks. */
- int sector;
- int sector_count;
+ uint64_t sector;
+ uint32_t sector_count;
/* The amounnt of data in the buffer. */
int buf_len;
uint8_t *dma_buf;
@@ -731,6 +731,9 @@ static int32_t scsi_send_command(SCSIDev
/* Returned value is the address of the last sector. */
if (nb_sectors) {
nb_sectors--;
+ /* Clip to 2TB, instead of returning capacity modulo 2TB. */
+ if (nb_sectors > UINT32_MAX)
+ nb_sectors = UINT32_MAX;
outbuf[0] = (nb_sectors >> 24) & 0xff;
outbuf[1] = (nb_sectors >> 16) & 0xff;
outbuf[2] = (nb_sectors >> 8) & 0xff;
--
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