[PATCH 04/14] scsi: core: Pick suitable allocation length in scsi_report_opcode()

Martin K. Petersen
2022-03-02T05:36:35Z

Some devices hang when a buffer size larger than expected is passed in
the ALLOCATION LENGTH field. For REPORT SUPPORTED OPERATION CODES we
currently only request a single command descriptor at a time and
therefore the actual size of the command is known ahead of time. Limit
the ALLOCATION LENGTH to the header size plus the command length of
the opcode we are asking about.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
---
drivers/scsi/scsi.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index af896d0647a7..c6221a2ca04e 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -508,21 +508,30 @@ int scsi_report_opcode(struct scsi_device *sdev, unsigned char *buffer,
{
unsigned char cmd[16];
struct scsi_sense_hdr sshdr;
- int result;
+ int result, request_len;

if (sdev->no_report_opcodes || sdev->scsi_level < SCSI_SPC_3)
return -EINVAL;

+ /* RSOC header + size of command we are asking about */
+ request_len = 4 + COMMAND_SIZE(opcode);
+ if (request_len > len) {
+ dev_warn_once(&sdev->sdev_gendev,
+ "%s: len %u bytes, opcode 0x%02x needs %u\n",
+ __func__, len, opcode, request_len);
+ return -EINVAL;
+ }
+
memset(cmd, 0, 16);
cmd[0] = MAINTENANCE_IN;
cmd[1] = MI_REPORT_SUPPORTED_OPERATION_CODES;
cmd[2] = 1; /* One command format */
cmd[3] = opcode;
- put_unaligned_be32(len, &cmd[6]);
+ put_unaligned_be32(request_len, &cmd[6]);
memset(buffer, 0, len);

- result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
- &sshdr, 30 * HZ, 3, NULL);
+ result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer,
+ request_len, &sshdr, 30 * HZ, 3, NULL);

if (result < 0)
return result;
--
2.32.0