2021-06-17 02:25:09

by Kees Cook

Subject: [PATCH] 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.

Signed-off-by: Kees Cook <[email protected]>
---
drivers/scsi/arcmsr/arcmsr_hba.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/arcmsr/arcmsr_hba.c b/drivers/scsi/arcmsr/arcmsr_hba.c
index e5149c9fd4e6..ec1a834c922d 100644
--- 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;
}
--
2.25.1

2021-06-19 19:32:32

by Martin K. Petersen

Subject: Re: [PATCH] scsi: arcmsr: Avoid over-read of sense buffer

Kees,

> 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.

Applied to 5.14/scsi-staging, thanks!

--
Martin K. Petersen Oracle Linux Engineering