From: Damien Le Moal <damien.lemoal@xxxxxxx> commit a7d6840bed0c2b16ac3071b74b5fcf08fc488241 upstream. The MODE SELECT(6) command allows handling mode page buffers that are up to 255 bytes, including the 4 byte header needed in front of the page buffer. For requests larger than this limit, automatically use the MODE SELECT(10) command. In both cases, since scsi_mode_select() adds the mode select page header, checks on the buffer length value must include this header size to avoid overflows of the command CDB allocation length field. While at it, use put_unaligned_be16() for setting the header block descriptor length and CDB allocation length when using MODE SELECT(10). [mkp: fix MODE SENSE vs. MODE SELECT confusion] Link: https://lore.kernel.org/r/20210820070255.682775-3-damien.lemoal@xxxxxxx Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx> Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Signed-off-by: Vasiliy Kovalev <kovalev@xxxxxxxxxxxx> --- kovalev: This patch complements the previously backported fixes e15de347faf4 ("scsi: core: Fix scsi_mode_sense() buffer length handling") and c82cd4eed128 ("scsi: sd: Fix sd_do_mode_sense() buffer length handling"), which are 2 out of 3 patches in the same series, one of which addressed the CVE-2021-47182 vulnerability. This patch introduces important changes to buffer length handling in scsi_mode_select(), completing the series and ensuring consistency and completeness of the fixes. Link: https://www.cve.org/CVERecord/?id=CVE-2021-47182 --- drivers/scsi/scsi_lib.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 2d37790321631b..9721984fd9bc68 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -2044,8 +2044,15 @@ scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage, memset(cmd, 0, sizeof(cmd)); cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0); - if (sdev->use_10_for_ms) { - if (len > 65535) + /* + * Use MODE SELECT(10) if the device asked for it or if the mode page + * and the mode select header cannot fit within the maximumm 255 bytes + * of the MODE SELECT(6) command. + */ + if (sdev->use_10_for_ms || + len + 4 > 255 || + data->block_descriptor_length > 255) { + if (len > 65535 - 8) return -EINVAL; real_buffer = kmalloc(8 + len, GFP_KERNEL); if (!real_buffer) @@ -2058,15 +2065,13 @@ scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage, real_buffer[3] = data->device_specific; real_buffer[4] = data->longlba ? 0x01 : 0; real_buffer[5] = 0; - real_buffer[6] = data->block_descriptor_length >> 8; - real_buffer[7] = data->block_descriptor_length; + put_unaligned_be16(data->block_descriptor_length, + &real_buffer[6]); cmd[0] = MODE_SELECT_10; - cmd[7] = len >> 8; - cmd[8] = len; + put_unaligned_be16(len, &cmd[7]); } else { - if (len > 255 || data->block_descriptor_length > 255 || - data->longlba) + if (data->longlba) return -EINVAL; real_buffer = kmalloc(4 + len, GFP_KERNEL); -- 2.33.8
