Re: [PATCH] esas2r: Use flex array destination for memcpy()

From: Gustavo A. R. Silva
Date: Thu Sep 01 2022 - 18:14:51 EST




On 9/1/22 15:57, Kees Cook wrote:
In preparation for FORTIFY_SOURCE performing run-time destination buffer
bounds checking for memcpy(), specify the destination output buffer
explicitly, instead of asking memcpy() to write past the end of what
looked like a fixed-size object. Silences future run-time warning:

memcpy: detected field-spanning write (size 80) of single field "trc + 1" (size 64)

There is no binary code output differences from this change.

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>

Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>

Thanks
--
Gustavo

---
drivers/scsi/esas2r/atioctl.h | 1 +
drivers/scsi/esas2r/esas2r_ioctl.c | 3 +--
2 files changed, 2 insertions(+), 2 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..e003d923acbf 100644
--- a/drivers/scsi/esas2r/esas2r_ioctl.c
+++ b/drivers/scsi/esas2r/esas2r_ioctl.c
@@ -947,10 +947,9 @@ static int hba_ioctl_callback(struct esas2r_adapter *a,
break;
}
- memcpy(trc + 1,
+ memcpy(trc->contents,
a->fw_coredump_buff + offset,
len);
-
hi->data_length = len;
} else if (trc->trace_func == ATTO_TRC_TF_RESET) {
memset(a->fw_coredump_buff, 0,