[PATCH 32/32] esas2r: Use __mem_to_flex() with struct atto_ioctl

[Kees Cook <keescook@xxxxxxxxxxxx>]

As part of the work to perform bounds checking on all memcpy() uses,
replace the open-coded a deserialization of bytes out of memory into a
trailing flexible array by using a flex_array.h helper to perform the
allocation, bounds checking, and copying. This requires adding the
flexible array explicitly.

Cc: Bradley Grove <linuxdrivers@xxxxxxxxxxxx>
Cc: "James E.J. Bottomley" <jejb@xxxxxxxxxxxxx>
Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>
Cc: linux-scsi@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 drivers/scsi/esas2r/atioctl.h      |  1 +
 drivers/scsi/esas2r/esas2r_ioctl.c | 11 +++++++----
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/esas2r/atioctl.h b/drivers/scsi/esas2r/atioctl.h
index ff2ad9b38575..dd3437412ffc 100644
--- a/drivers/scsi/esas2r/atioctl.h
+++ b/drivers/scsi/esas2r/atioctl.h
@@ -831,6 +831,7 @@ struct __packed atto_hba_trace {
        u32 total_length;
        u32 trace_mask;
        u8 reserved2[48];
+       u8 contents[];
 };
 
 #define ATTO_FUNC_SCSI_PASS_THRU     0x04
diff --git a/drivers/scsi/esas2r/esas2r_ioctl.c 
b/drivers/scsi/esas2r/esas2r_ioctl.c
index 08f4e43c7d9e..9310b54b1575 100644
--- a/drivers/scsi/esas2r/esas2r_ioctl.c
+++ b/drivers/scsi/esas2r/esas2r_ioctl.c
@@ -947,11 +947,14 @@ static int hba_ioctl_callback(struct esas2r_adapter *a,
                                        break;
                                }
 
-                               memcpy(trc + 1,
-                                      a->fw_coredump_buff + offset,
-                                      len);
+                               if (__mem_to_flex(hi, data.trace.contents,
+                                                 data_length,
+                                                 a->fw_coredump_buff + offset,
+                                                 len)) {
+                                       hi->status = ATTO_STS_INV_FUNC;
+                                       break;
+                               }
 
-                               hi->data_length = len;
                        } else if (trc->trace_func == ATTO_TRC_TF_RESET) {
                                memset(a->fw_coredump_buff, 0,
                                       ESAS2R_FWCOREDUMP_SZ);
-- 
2.32.0