From a00a7862513089f17209b732f230922f1942e0b9 Mon Sep 17 00:00:00 2001 From: "Martin K. Petersen" Date: Fri, 17 Mar 2017 08:47:14 -0400 Subject: [PATCH] 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: Reported-by: Kefeng Wang Tested-by: Kefeng Wang Signed-off-by: Martin K. Petersen --- drivers/scsi/sr.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c index 0b29b9329b1c..a8f630213a1a 100644 --- a/drivers/scsi/sr.c +++ b/drivers/scsi/sr.c @@ -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 | -- 2.20.1