From 0d60bc71e6a757f15f63bd6331752f8bd551154d 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 BugLink: http://bugs.launchpad.net/bugs/1687045 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 Signed-off-by: Stefan Bader Signed-off-by: Thadeu Lima de Souza Cascardo --- 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 94352e4df831..94b0aacefae6 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 | -- 2.39.2