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scsi: sr: Sanity check returned mode data 

Kefeng Wang discovered that old versions of the QEMU CD driver would
return mangled mode data causing us to walk off the end of the buffer in
an attempt to parse it. Sanity check the returned mode sense data.

Cc: <stable@vger.kernel.org>
Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Martin K. Petersen 2017-03-17 08:47:14 -04:00
parent 6780414519
commit a00a786251
1 changed files with 4 additions and 2 deletions
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6
drivers/scsi/sr.c
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@ -836,6 +836,7 @@ static void get_capabilities(struct scsi_cd *cd)
unsigned char *buffer;
struct scsi_mode_data data;
struct scsi_sense_hdr sshdr;
unsigned int ms_len = 128;
int rc, n;
static const char *loadmech[] =
@ -862,10 +863,11 @@ static void get_capabilities(struct scsi_cd *cd)
scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr);
/* ask for mode page 0x2a */
rc = scsi_mode_sense(cd->device, 0, 0x2a, buffer, 128,
rc = scsi_mode_sense(cd->device, 0, 0x2a, buffer, ms_len,
SR_TIMEOUT, 3, &data, NULL);
if (!scsi_status_is_good(rc)) {
if (!scsi_status_is_good(rc) || data.length > ms_len ||
data.header_length + data.block_descriptor_length > data.length) {
/* failed, drive doesn't have capabilities mode page */
cd->cdi.speed = 1;
cd->cdi.mask |= (CDC_CD_R | CDC_CD_RW | CDC_DVD_R |