@@ -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 SENSE 10 if the device asked for it or if the mode page
+ * and the mode select header cannot fit within the maximumm 255B 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);
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 SENSE 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 allocatione 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. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> --- drivers/scsi/scsi_lib.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-)