spi/spidev: check message size before copying

Message size needs to be checked before copying, or bad things could
happen.

Signed-off-by: Domen Puncer <domen.puncer@telargo.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index 225d6b2f82dd..bcfef04f547e 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -168,6 +168,12 @@ static int spidev_message(struct spidev_data *spidev,
                         n--, k_tmp++, u_tmp++) {
                 k_tmp->len = u_tmp->len;
 
+                total += k_tmp->len;
+                if (total > bufsiz) {
+                        status = -EMSGSIZE;
+                        goto done;
+                }
+
                 if (u_tmp->rx_buf) {
                         k_tmp->rx_buf = buf;
                         if (!access_ok(VERIFY_WRITE, u_tmp->rx_buf, u_tmp->len))
@@ -179,12 +185,6 @@ static int spidev_message(struct spidev_data *spidev,
                                         u_tmp->len))
                                 goto done;
                 }
-
-                total += k_tmp->len;
-                if (total > bufsiz) {
-                        status = -EMSGSIZE;
-                        goto done;
-                }
                 buf += k_tmp->len;
 
                 k_tmp->cs_change = !!u_tmp->cs_change;