| Message ID | 1488536272-10509-1-git-send-email-wangkefeng.wang@huawei.com |
|---|---|
| State | New |
| Headers | show |
Kefeng Wang <wangkefeng.wang@huawei.com> writes: Kefeng, > 'n = header_length + block_descriptor_length' could be greater than 512, > and will lead to oob access, so enlarge transfer buffer to fix it. Can you share the output of sg_modes -p 0x2a /dev/srN for the offending drive? This mode page is usually much smaller than 512 bytes (typically between 32 and 128 bytes). -- Martin K. Petersen Oracle Linux Engineering
On 2017/3/16 8:07, Martin K. Petersen wrote: > Kefeng Wang <wangkefeng.wang@huawei.com> writes: > > Kefeng, > >> 'n = header_length + block_descriptor_length' could be greater than 512, >> and will lead to oob access, so enlarge transfer buffer to fix it. > > Can you share the output of sg_modes -p 0x2a /dev/srN for the offending > drive? root@localhost ~]# sg_modes -p 0x2a /dev/sr0 QEMU QEMU DVD-ROM 0.15 peripheral_type: cd/dvd [0x5] Mode parameter header from MODE SENSE(10): Invalid block descriptor length=512, ignore Mode data length=36, medium type=0x70, specific param=0x00, longlba=0 Block descriptor length=0 >> MM capabilities and mechanical status (obsolete), page_control: current 00 2a 12 00 00 71 60 29 00 02 c2 00 02 02 00 02 c2 10 00 00 00 00 Unexpectedly received extra mode page responses, ignore note: the issue was found in guestos? maybe some bugs exist in qemu? Kefeng > > This mode page is usually much smaller than 512 bytes (typically between > 32 and 128 bytes). >
On 2017/3/18 7:29, Martin K. Petersen wrote: > Kefeng Wang <wangkefeng.wang@huawei.com> writes: > > Kefeng, > >> root@localhost ~]# sg_modes -p 0x2a /dev/sr0 >> QEMU QEMU DVD-ROM 0.15 peripheral_type: cd/dvd [0x5] >> Mode parameter header from MODE SENSE(10): >> Invalid block descriptor length=512, ignore >> Mode data length=36, medium type=0x70, specific param=0x00, longlba=0 >> Block descriptor length=0 >>>> MM capabilities and mechanical status (obsolete), page_control: current >> 00 2a 12 00 00 71 60 29 00 02 c2 00 02 02 00 02 c2 >> 10 00 00 00 00 >> Unexpectedly received extra mode page responses, ignore > > That looks pretty broken. > > Could you try the following patch? The issue still exists, the patch return zero in scsi_mode_sense(), but zero means SAM_STAT_GOOD in scsi_status_is_good(), so n will be still bigger than 512; Thanks,
Kefeng Wang <wangkefeng.wang@huawei.com> writes: Kefeng, > The issue still exists, the patch return zero in scsi_mode_sense(), but zero means > SAM_STAT_GOOD in scsi_status_is_good(), so n will be still bigger than 512; OK, I checked the other users of scsi_mode_sense(). So let's keep this fix local to sr.c for now. How about the following? 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: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>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 |
On 2017/3/20 22:29, Martin K. Petersen wrote: > Kefeng Wang <wangkefeng.wang@huawei.com> writes: > > Kefeng, > >> The issue still exists, the patch return zero in scsi_mode_sense(), but zero means >> SAM_STAT_GOOD in scsi_status_is_good(), so n will be still bigger than 512; > > OK, I checked the other users of scsi_mode_sense(). So let's keep this > fix local to sr.c for now. > > How about the following? > > > 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: Kefeng Wang <wangkefeng.wang@huawei.com> > Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> > > 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); > move n = data.header_length + data.block_descriptor_length; here, > - 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) { n > data.length Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com> Thanks, Kefeng > /* failed, drive doesn't have capabilities mode page */ > cd->cdi.speed = 1; > cd->cdi.mask |= (CDC_CD_R | CDC_CD_RW | CDC_DVD_R | > > > > . >
=== BUG: KASAN: slab-out-of-bounds in sr_probe+0x570/0xcc0 at addr ffff88000009020e Read of size 1 by task kworker/u48:2/188 Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> --- drivers/scsi/sr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c index 0b29b93..5a80aa6 100644 --- a/drivers/scsi/sr.c +++ b/drivers/scsi/sr.c @@ -852,7 +852,7 @@ static void get_capabilities(struct scsi_cd *cd) /* allocate transfer buffer */ - buffer = kmalloc(512, GFP_KERNEL | GFP_DMA); + buffer = kmalloc(1024, GFP_KERNEL | GFP_DMA); if (!buffer) { sr_printk(KERN_ERR, cd, "out of memory.\n"); return;