Commit 584063be authored by Martin K. Petersen's avatar Martin K. Petersen Committed by Ben Hutchings

scsi: sr: Sanity check returned mode data

commit a00a7862 upstream.

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.
Reported-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Tested-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent 581ebc29
...@@ -815,6 +815,7 @@ static void get_capabilities(struct scsi_cd *cd) ...@@ -815,6 +815,7 @@ static void get_capabilities(struct scsi_cd *cd)
unsigned char *buffer; unsigned char *buffer;
struct scsi_mode_data data; struct scsi_mode_data data;
struct scsi_sense_hdr sshdr; struct scsi_sense_hdr sshdr;
unsigned int ms_len = 128;
int rc, n; int rc, n;
static const char *loadmech[] = static const char *loadmech[] =
...@@ -841,10 +842,11 @@ static void get_capabilities(struct scsi_cd *cd) ...@@ -841,10 +842,11 @@ static void get_capabilities(struct scsi_cd *cd)
scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr); scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr);
/* ask for mode page 0x2a */ /* 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); 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 */ /* failed, drive doesn't have capabilities mode page */
cd->cdi.speed = 1; cd->cdi.speed = 1;
cd->cdi.mask |= (CDC_CD_R | CDC_CD_RW | CDC_DVD_R | cd->cdi.mask |= (CDC_CD_R | CDC_CD_RW | CDC_DVD_R |
......
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