staging: rts5208: Fix get_ms_information() heap buffer size

Fix buf allocation size (it needs to be 2 bytes larger). Found when
__alloc_size() annotations were added to kmalloc() interfaces.

In file included from ./include/linux/string.h:253,
                 from ./include/linux/bitmap.h:10,
                 from ./include/linux/cpumask.h:12,
                 from ./arch/x86/include/asm/paravirt.h:17,
                 from ./arch/x86/include/asm/irqflags.h:63,
                 from ./include/linux/irqflags.h:16,
                 from ./include/linux/rcupdate.h:26,
                 from ./include/linux/rculist.h:11,
                 from ./include/linux/pid.h:5,
                 from ./include/linux/sched.h:14,
                 from ./include/linux/blkdev.h:5,
                 from drivers/staging/rts5208/rtsx_scsi.c:12:
In function 'get_ms_information',
    inlined from 'ms_sp_cmnd' at drivers/staging/rts5208/rtsx_scsi.c:2877:12,
    inlined from 'rtsx_scsi_handler' at drivers/staging/rts5208/rtsx_scsi.c:3247:12:
./include/linux/fortify-string.h:54:29: warning: '__builtin_memcpy' forming offset [106, 107] is out
 of the bounds [0, 106] [-Warray-bounds]
   54 | #define __underlying_memcpy __builtin_memcpy
      |                             ^
./include/linux/fortify-string.h:417:2: note: in expansion of macro '__underlying_memcpy'
  417 |  __underlying_##op(p, q, __fortify_size);   \
      |  ^~~~~~~~~~~~~
./include/linux/fortify-string.h:463:26: note: in expansion of macro '__fortify_memcpy_chk'
  463 | #define memcpy(p, q, s)  __fortify_memcpy_chk(p, q, s,   \
      |                          ^~~~~~~~~~~~~~~~~~~~
drivers/staging/rts5208/rtsx_scsi.c:2851:3: note: in expansion of macro 'memcpy'
 2851 |   memcpy(buf + i, ms_card->raw_sys_info, 96);
      |   ^~~~~~

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-staging@lists.linux.dev
Signed-off-by: NKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210818044252.1533634-1-keescook@chromium.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rts5208/rtsx_scsi.c

@@ -2802,10 +2802,10 @@ static int get_ms_information(struct scsi_cmnd *srb, struct rtsx_chip *chip)
 	}
 
 	if (dev_info_id == 0x15) {
-		buf_len = 0x3A;
+		buf_len = 0x3C;
 		data_len = 0x3A;
 	} else {
-		buf_len = 0x6A;
+		buf_len = 0x6C;
 		data_len = 0x6A;
 	}
 
@@ -2855,11 +2855,7 @@ static int get_ms_information(struct scsi_cmnd *srb, struct rtsx_chip *chip)
 	}
 
 	rtsx_stor_set_xfer_buf(buf, buf_len, srb);
-
-	if (dev_info_id == 0x15)
-		scsi_set_resid(srb, scsi_bufflen(srb) - 0x3C);
-	else
-		scsi_set_resid(srb, scsi_bufflen(srb) - 0x6C);
+	scsi_set_resid(srb, scsi_bufflen(srb) - buf_len);
 
 	kfree(buf);
 	return STATUS_SUCCESS;