net/packet: fix overflow in tpacket_rcv

Using tp_reserve to calculate netoff can overflow as
tp_reserve is unsigned int and netoff is unsigned short.

This may lead to macoff receving a smaller value then
sizeof(struct virtio_net_hdr), and if po->has_vnet_hdr
is set, an out-of-bounds write will occur when
calling virtio_net_hdr_from_skb.

The bug is fixed by converting netoff to unsigned int
and checking if it exceeds USHRT_MAX.

TEST=Manually tried the reproducer before and after this fix.
RELEASE_NOTE=Fixed overflow in tpacket_rcv, which caused

Fixes: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt")
Signed-off-by: Or Cohen <>
Signed-off-by: Roy Yang <>
Change-Id: I119b9e950f948259bbf0e3afeda5f33c0fb40e51
Reviewed-by: Vaibhav Rustagi <>
Reviewed-by: Robert Kolchmeyer <>
Tested-by: Robert Kolchmeyer <>
(cherry picked from commit 4d64e87ddd30cd19fb16caaae5cc3fc81a135e16)
Tested-by: Vaibhav Rustagi <>
1 file changed