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> --- 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 0a9db3464fd48e..06838cf5300d00 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -2019,8 +2019,15 @@ 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) @@ -2033,15 +2040,13 @@ 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
