kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-10-20 19:23:40 +00:00
Code Issues Releases Packages Activity
linux/net/packet
History
Bingquan Chen 714aa973da net/packet: fix TOCTOU race on mmap'd vnet_hdr in tpacket_snd() 
[ Upstream commit 2c054e17d9 ]

In tpacket_snd(), when PACKET_VNET_HDR is enabled, vnet_hdr points
directly into the mmap'd TX ring buffer shared with userspace. The
kernel validates the header via __packet_snd_vnet_parse() but then
re-reads all fields later in virtio_net_hdr_to_skb(). A concurrent
userspace thread can modify the vnet_hdr fields between validation
and use, bypassing all safety checks.

The non-TPACKET path (packet_snd()) already correctly copies vnet_hdr
to a stack-local variable. All other vnet_hdr consumers in the kernel
(tun.c, tap.c, virtio_net.c) also use stack copies. The TPACKET TX
path is the only caller of virtio_net_hdr_to_skb() that reads directly
from user-controlled shared memory.

Fix this by copying vnet_hdr from the mmap'd ring buffer to a
stack-local variable before validation and use, consistent with the
approach used in packet_snd() and all other callers.

Fixes: 1d036d25e5 ("packet: tpacket_snd gso and checksum offload")
Signed-off-by: Bingquan Chen <patzilla007@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260418112006.78823-1-patzilla007@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ replaced `vnet_hdr_sz` with `sizeof(vnet_hdr)` and `if (vnet_hdr_sz)` with `if (po->has_vnet_hdr)` ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2026-06-19 13:33:40 +02:00
..
af_packet.c net/packet: fix TOCTOU race on mmap'd vnet_hdr in tpacket_snd() 2026-06-19 13:33:40 +02:00
diag.c af_packet: Fix data-races of pkt_sk(sk)->num. 2023-06-09 10:32:16 +02:00
internal.h packet: Move reference count in packet_sock to atomic_long_t 2023-12-13 18:36:43 +01:00
Kconfig treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00