To avoid overwriting the upper bits of the flags, commit
39ec7de7092b ("macvtap: fix uninitialized access on
TUNSETIFF") changed the variable u from unsigned int to
unsigned short and added some ORing logic for the flags.
This introduced at least one regression:
- TUNSETSNDBUF supports int as its size and also uses the now
short u as buffer - this breaks any sendbuf size > 64k
Let's change u back to unsigned int, keep the ORing and
handle the overwrite issue with casts and masking.
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Reported-by: Mark A. Peloquin
Bisected-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Fixes: 39ec7de7092b ("macvtap: fix uninitialized access on TUNSETIFF")
Cc: stable@xxxxxxxxxxxxxxx
---
drivers/net/macvtap.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index edd7734..c33fe41 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -1060,7 +1060,7 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
void __user *argp = (void __user *)arg;
struct ifreq __user *ifr = argp;
unsigned int __user *up = argp;
- unsigned short u;
+ unsigned int u;
int __user *sp = argp;
struct sockaddr sa;
int s;
@@ -1076,7 +1076,7 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
if ((u & ~MACVTAP_FEATURES) != (IFF_NO_PI | IFF_TAP))
ret = -EINVAL;
else
- q->flags = (q->flags & ~MACVTAP_FEATURES) | u;
+ q->flags = (q->flags & ~MACVTAP_FEATURES) | (short) u;
return ret;
@@ -1089,9 +1089,8 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
}
ret = 0;
- u = q->flags;
if (copy_to_user(&ifr->ifr_name, vlan->dev->name, IFNAMSIZ) ||
- put_user(u, &ifr->ifr_flags))
+ put_user((short) q->flags, &ifr->ifr_flags))
ret = -EFAULT;
macvtap_put_vlan(vlan);
rtnl_unlock();
--
2.3.0
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