macvtap: fix TUNSETSNDBUF values > 64k

commit 3ea79249e81e5ed051f2e6480cbde896d99046e8 upstream.

Upon TUNSETSNDBUF,  macvtap reads the requested sndbuf size into
a local variable u.
commit 39ec7de7092b ("macvtap: fix uninitialized access on
TUNSETIFF") changed its type to u16 (which is the right thing to
do for all other macvtap ioctls), breaking all values > 64k.

The value of TUNSETSNDBUF is actually a signed 32 bit integer, so
the right thing to do is to read it into an int.

Cc: David S. Miller <davem@davemloft.net>
Fixes: 39ec7de7092b ("macvtap: fix uninitialized access on TUNSETIFF")
Reported-by: Mark A. Peloquin
Bisected-by: Matthew Rosato <mjrosato@linux.vnet.ibm.com>
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by:  Matthew Rosato <mjrosato@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 1c3db94e42371352cb954648f9fe0eaac6c815a8..4cfd8e583cd55e1d3813a3d7d0921ba57ed03582 100644 (file)
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -951,10 +951,10 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
                return 0;
 
        case TUNSETSNDBUF:
-               if (get_user(u, up))
+               if (get_user(s, sp))
                        return -EFAULT;
 
-               q->sk.sk_sndbuf = u;
+               q->sk.sk_sndbuf = s;
                return 0;
 
        case TUNGETVNETHDRSZ: