can: Fix copy_from_user() results interpretation

Both copy_to_ and _from_user return the number of bytes, that failed to
reach their destination, not the 0/-EXXX values.

Based on patch from Pavel Emelyanov <xemul@openvz.org>

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/can/raw.c b/net/can/raw.c
index 201cbfc..69877b8 100644 (file)
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -435,15 +435,13 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
                        if (!filter)
                                return -ENOMEM;
 
-                       err = copy_from_user(filter, optval, optlen);
-                       if (err) {
+                       if (copy_from_user(filter, optval, optlen)) {
                                kfree(filter);
-                               return err;
+                               return -EFAULT;
                        }
                } else if (count == 1) {
-                       err = copy_from_user(&sfilter, optval, optlen);
-                       if (err)
-                               return err;
+                       if (copy_from_user(&sfilter, optval, optlen))
+                               return -EFAULT;
                }
 
                lock_sock(sk);
@@ -493,9 +491,8 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
                if (optlen != sizeof(err_mask))
                        return -EINVAL;
 
-               err = copy_from_user(&err_mask, optval, optlen);
-               if (err)
-                       return err;
+               if (copy_from_user(&err_mask, optval, optlen))
+                       return -EFAULT;
 
                err_mask &= CAN_ERR_MASK;
 
@@ -531,7 +528,8 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
                if (optlen != sizeof(ro->loopback))
                        return -EINVAL;
 
-               err = copy_from_user(&ro->loopback, optval, optlen);
+               if (copy_from_user(&ro->loopback, optval, optlen))
+                       return -EFAULT;
 
                break;
 
@@ -539,7 +537,8 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
                if (optlen != sizeof(ro->recv_own_msgs))
                        return -EINVAL;
 
-               err = copy_from_user(&ro->recv_own_msgs, optval, optlen);
+               if (copy_from_user(&ro->recv_own_msgs, optval, optlen))
+                       return -EFAULT;
 
                break;