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Commit a00a7862 authored by Martin K. Petersen's avatar Martin K. Petersen
Browse files

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: 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>
parent 67804145

drivers/scsi/sr.c

+4 −2
Original line number Diff line number Diff line
@@ -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 |