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scsi: megaraid_sas: Add flexible array member for SGLs

PATCH Applied Kees Cook 3 participants 4 messages Jan 6, 2023 – Jan 27, 2023

Subsystems (2)
SCSI Megaraid SCSI/SAS drivers
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Kees Cook

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#0 lore raw

PATCH 1/1 scsi: megaraid_sas: Add flexible array member for SGLs

struct MPI2_RAID_SCSI_IO_REQUEST ends with a single SGL, but expects to copy multiple. Add a flexible array member so the compiler can reason about the size of the memcpy(). This will avoid the run-time false positive warning:

memcpy: detected field-spanning write (size 128) of single field "&r1_cmd->io_request->SGL" at drivers/scsi/megaraid/megaraid_sas_fusion.c:3326 (size 16)

This change results in no binary output differences.

Reported-by Holger Kiehl <[email protected]>
Link https://lore.kernel.org/all/[email protected]/ open here
Cc Kashyap Desai <[email protected]>
Cc Sumit Saxena <[email protected]>
Cc Shivasharan S <[email protected]>
Cc "James E.J. Bottomley" <[email protected]>
Cc "Martin K. Petersen" <[email protected]>
Cc [email protected]
Cc [email protected]
Signed-off-by Kees Cook <[email protected]>

---
Holger, are you able to test this change? I expect it should do the trick, but I don't have the hardware.

---
 drivers/scsi/megaraid/megaraid_sas_fusion.c | 2 +-
 drivers/scsi/megaraid/megaraid_sas_fusion.h | 5 ++++-
 2 files changed, 5 insertions(+), 2 deletions(-)
drivers/scsi/megaraid/megaraid_sas_fusion.c +1 -1
index fe70f8f11435..6597e118c805 100644
@@ -3323,7 +3323,7 @@ static void megasas_prepare_secondRaid1_IO(struct megasas_instance *instance,
 	/* copy the io request frame as well as 8 SGEs data for r1 command*/
 	memcpy(r1_cmd->io_request, cmd->io_request,
 	       (sizeof(struct MPI2_RAID_SCSI_IO_REQUEST)));
-	memcpy(&r1_cmd->io_request->SGL, &cmd->io_request->SGL,
+	memcpy(r1_cmd->io_request->SGLs, cmd->io_request->SGLs,
 	       (fusion->max_sge_in_main_msg * sizeof(union MPI2_SGE_IO_UNION)));
 	/*sense buffer is different for r1 command*/
 	r1_cmd->io_request->SenseBufferLowAddress =
drivers/scsi/megaraid/megaraid_sas_fusion.h +4 -1
index 49e9a9048ee7..b677d80e5874 100644
@@ -526,7 +526,10 @@ struct MPI2_RAID_SCSI_IO_REQUEST {
 	__le32			Control;                        /* 0x3C */
 	union MPI2_SCSI_IO_CDB_UNION  CDB;			/* 0x40 */
 	union RAID_CONTEXT_UNION RaidContext;  /* 0x60 */
-	union MPI2_SGE_IO_UNION       SGL;			/* 0x80 */
+	union {
+		union MPI2_SGE_IO_UNION       SGL;		/* 0x80 */
+		DECLARE_FLEX_ARRAY(union MPI2_SGE_IO_UNION, SGLs);
+	};
 };
 
 /*
Signature · 1 line
2.34.1
#1 lore raw
Quoted 19 lines · Kees Cook

struct MPI2_RAID_SCSI_IO_REQUEST ends with a single SGL, but expects to copy multiple. Add a flexible array member so the compiler can reason about the size of the memcpy(). This will avoid the run-time false positive warning:

memcpy: detected field-spanning write (size 128) of single field "&r1_cmd->io_request->SGL" at drivers/scsi/megaraid/megaraid_sas_fusion.c:3326 (size 16)

This change results in no binary output differences.

Reported-by Holger Kiehl <[email protected]>
Link https://lore.kernel.org/all/[email protected]/ open here
Cc Kashyap Desai <[email protected]>
Cc Sumit Saxena <[email protected]>
Cc Shivasharan S <[email protected]>
Cc "James E.J. Bottomley" <[email protected]>
Cc "Martin K. Petersen" <[email protected]>
Cc [email protected]
Cc [email protected]
Signed-off-by Kees Cook <[email protected]>
Quoted 4 lines

---
Holger, are you able to test this change? I expect it should do the trick, but I don't have the hardware.

Yes, that does work. I no longer see 'memcpy: detected field-spanning write (size 128)'. Tested this on 6.1.4-rc1. Did not see any other regression.

Regards,
Holger

Applied
#2 lore raw
In reply to Kees Cook

Kees,

Quoted 4 lines

struct MPI2_RAID_SCSI_IO_REQUEST ends with a single SGL, but expects to copy multiple. Add a flexible array member so the compiler can reason about the size of the memcpy(). This will avoid the run-time false positive warning:

Applied to 6.3/scsi-staging, thanks!

Signature · 1 line
Martin K. Petersen	Oracle Linux Engineering
Applied
#3 lore raw
In reply to Kees Cook
Quoted 8 lines · Kees Cook

struct MPI2_RAID_SCSI_IO_REQUEST ends with a single SGL, but expects to copy multiple. Add a flexible array member so the compiler can reason about the size of the memcpy(). This will avoid the run-time false positive warning:

memcpy: detected field-spanning write (size 128) of single field "&r1_cmd->io_request->SGL" at drivers/scsi/megaraid/megaraid_sas_fusion.c:3326 (size 16)

[...]

Applied to 6.3/scsi-queue, thanks!

[1/1] scsi: megaraid_sas: Add flexible array member for SGLs

      https://git.kernel.org/mkp/scsi/c/a9a3629592ab
Signature · 1 line
Martin K. Petersen	Oracle Linux Engineering