From a7d6840bed0c2b16ac3071b74b5fcf08fc488241 Mon Sep 17 00:00:00 2001 From: Damien Le Moal Date: Fri, 20 Aug 2021 16:02:54 +0900 Subject: [PATCH] scsi: core: Fix scsi_mode_select() buffer length handling 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@wdc.com Signed-off-by: Damien Le Moal Signed-off-by: Martin K. Petersen --- 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 701d8e8480f22c..dcf105287a7686 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -2026,8 +2026,15 @@ 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) @@ -2040,15 +2047,13 @@ 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);