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>

1 files changed, 10 insertions, 11 deletions

diff --git a/net/can/raw.c b/net/can/raw.c
index 201cbfc6b9ec..69877b8e7e9c 100644
--- 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;