scsi: arcmsr: Avoid over-read of sense buffer

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
intentionally reading across neighboring array fields.

pcmd->sense_buffer is 96 bytes, and was being manually zero-filled.
However, struct SENSE_DATA is 18 bytes, with ccb->arcmsr_cdb.SenseData only
being 15 bytes, resulting in a 3 byte over-read.

Copy only the contents of ccb->arcmsr_cdb.SenseData and zero fill the
remainder, avoiding potential over-reads.

Link: https://lore.kernel.org/r/20210616212428.1726958-1-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/arcmsr/arcmsr_hba.c b/drivers/scsi/arcmsr/arcmsr_hba.c
index e5149c9..ec1a834 100644 (file)
--- a/drivers/scsi/arcmsr/arcmsr_hba.c
+++ b/drivers/scsi/arcmsr/arcmsr_hba.c
@@ -1323,16 +1323,19 @@ static void arcmsr_ccb_complete(struct CommandControlBlock *ccb)
 
 static void arcmsr_report_sense_info(struct CommandControlBlock *ccb)
 {
-
        struct scsi_cmnd *pcmd = ccb->pcmd;
-       struct SENSE_DATA *sensebuffer = (struct SENSE_DATA *)pcmd->sense_buffer;
+
        pcmd->result = (DID_OK << 16) | SAM_STAT_CHECK_CONDITION;
-       if (sensebuffer) {
-               int sense_data_length =
-                       sizeof(struct SENSE_DATA) < SCSI_SENSE_BUFFERSIZE
-                       ? sizeof(struct SENSE_DATA) : SCSI_SENSE_BUFFERSIZE;
-               memset(sensebuffer, 0, SCSI_SENSE_BUFFERSIZE);
-               memcpy(sensebuffer, ccb->arcmsr_cdb.SenseData, sense_data_length);
+       if (pcmd->sense_buffer) {
+               struct SENSE_DATA *sensebuffer;
+
+               memcpy_and_pad(pcmd->sense_buffer,
+                              SCSI_SENSE_BUFFERSIZE,
+                              ccb->arcmsr_cdb.SenseData,
+                              sizeof(ccb->arcmsr_cdb.SenseData),
+                              0);
+
+               sensebuffer = (struct SENSE_DATA *)pcmd->sense_buffer;
                sensebuffer->ErrorCode = SCSI_SENSE_CURRENT_ERRORS;
                sensebuffer->Valid = 1;
        }