tree 8bab123fbc0045c7fb88e211a4b1b639d1651c09
parent f3d4a28d6b04a73d713c42ccb874194336d8c32d
author Or Cohen <orcohen@paloaltonetworks.com> 1598807091 +0300
committer Vaibhav Rustagi <vaibhavrustagi@google.com> 1599184276 +0000

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.

BUG=b/167730744
TEST=Manually tried the reproducer before and after this fix.
RELEASE_NOTE=Fixed overflow in tpacket_rcv, which caused
CVE-2020-14386.
SOURCE=FROMLIST(https://www.openwall.com/lists/oss-security/2020/09/03/3)

Fixes: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt")
Signed-off-by: Or Cohen <orcohen@paloaltonetworks.com>
Signed-off-by: Roy Yang <royyang@google.com>
Change-Id: I119b9e950f948259bbf0e3afeda5f33c0fb40e51
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/4981
Reviewed-by: Vaibhav Rustagi <vaibhavrustagi@google.com>
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Tested-by: Robert Kolchmeyer <rkolchmeyer@google.com>
(cherry picked from commit 4d64e87ddd30cd19fb16caaae5cc3fc81a135e16)
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/4982
Tested-by: Vaibhav Rustagi <vaibhavrustagi@google.com>