From c80c158bfe613d346d48803462bf55d8f35d228e Mon Sep 17 00:00:00 2001 From: "Martin K. Petersen" Date: Fri, 17 Mar 2017 08:47:14 -0400 Subject: scsi: sr: Sanity check returned mode data commit a00a7862513089f17209b732f230922f1942e0b9 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: Kefeng Wang Tested-by: Kefeng Wang Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c index bed2bbd..e635973 100644 --- a/drivers/scsi/sr.c +++ b/drivers/scsi/sr.c @@ -833,6 +833,7 @@ 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[] = @@ -859,10 +860,11 @@ 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 | -- cgit v0.10.2