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* [PATCH] scsi: arcmsr: Avoid over-read of sense buffer
@ 2021-06-16 21:24 Kees Cook
  2021-06-19  3:29 ` Martin K. Petersen
  0 siblings, 1 reply; 2+ messages in thread
From: Kees Cook @ 2021-06-16 21:24 UTC (permalink / raw)
  To: Martin K. Petersen
  Cc: Kees Cook, James E.J. Bottomley, ching Huang, Lee Jones,
	Vaibhav Gupta, Hannes Reinecke, Gustavo A. R. Silva,
	linux-kernel, linux-scsi, linux-hardening

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 <keescook@chromium.org>
---
 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


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] scsi: arcmsr: Avoid over-read of sense buffer
  2021-06-16 21:24 [PATCH] scsi: arcmsr: Avoid over-read of sense buffer Kees Cook
@ 2021-06-19  3:29 ` Martin K. Petersen
  0 siblings, 0 replies; 2+ messages in thread
From: Martin K. Petersen @ 2021-06-19  3:29 UTC (permalink / raw)
  To: Kees Cook
  Cc: Martin K. Petersen, James E.J. Bottomley, ching Huang, Lee Jones,
	Vaibhav Gupta, Hannes Reinecke, Gustavo A. R. Silva,
	linux-kernel, linux-scsi, linux-hardening


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

^ permalink raw reply	[flat|nested] 2+ messages in thread

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