linux/include
Willem de Bruijn 413e785a89 net: drop bad gso csum_start and offset in virtio_net_hdr
[ Upstream commit 89add40066 ]

Tighten csum_start and csum_offset checks in virtio_net_hdr_to_skb
for GSO packets.

The function already checks that a checksum requested with
VIRTIO_NET_HDR_F_NEEDS_CSUM is in skb linear. But for GSO packets
this might not hold for segs after segmentation.

Syzkaller demonstrated to reach this warning in skb_checksum_help

	offset = skb_checksum_start_offset(skb);
	ret = -EINVAL;
	if (WARN_ON_ONCE(offset >= skb_headlen(skb)))

By injecting a TSO packet:

WARNING: CPU: 1 PID: 3539 at net/core/dev.c:3284 skb_checksum_help+0x3d0/0x5b0
 ip_do_fragment+0x209/0x1b20 net/ipv4/ip_output.c:774
 ip_finish_output_gso net/ipv4/ip_output.c:279 [inline]
 __ip_finish_output+0x2bd/0x4b0 net/ipv4/ip_output.c:301
 iptunnel_xmit+0x50c/0x930 net/ipv4/ip_tunnel_core.c:82
 ip_tunnel_xmit+0x2296/0x2c70 net/ipv4/ip_tunnel.c:813
 __gre_xmit net/ipv4/ip_gre.c:469 [inline]
 ipgre_xmit+0x759/0xa60 net/ipv4/ip_gre.c:661
 __netdev_start_xmit include/linux/netdevice.h:4850 [inline]
 netdev_start_xmit include/linux/netdevice.h:4864 [inline]
 xmit_one net/core/dev.c:3595 [inline]
 dev_hard_start_xmit+0x261/0x8c0 net/core/dev.c:3611
 __dev_queue_xmit+0x1b97/0x3c90 net/core/dev.c:4261
 packet_snd net/packet/af_packet.c:3073 [inline]

The geometry of the bad input packet at tcp_gso_segment:

[   52.003050][ T8403] skb len=12202 headroom=244 headlen=12093 tailroom=0
[   52.003050][ T8403] mac=(168,24) mac_len=24 net=(192,52) trans=244
[   52.003050][ T8403] shinfo(txflags=0 nr_frags=1 gso(size=1552 type=3 segs=0))
[   52.003050][ T8403] csum(0x60000c7 start=199 offset=1536
ip_summed=3 complete_sw=0 valid=0 level=0)

Mitigate with stricter input validation.

csum_offset: for GSO packets, deduce the correct value from gso_type.
This is already done for USO. Extend it to TSO. Let UFO be:
udp[46]_ufo_fragment ignores these fields and always computes the
checksum in software.

csum_start: finding the real offset requires parsing to the transport
header. Do not add a parser, use existing segmentation parsing. Thanks
to SKB_GSO_DODGY, that also catches bad packets that are hw offloaded.
Again test both TSO and USO. Do not test UFO for the above reason, and
do not test UDP tunnel offload.

GSO packet are almost always CHECKSUM_PARTIAL. USO packets may be
CHECKSUM_NONE since commit 10154dbded ("udp: Allow GSO transmit
from devices with no checksum offload"), but then still these fields
are initialized correctly in udp4_hwcsum/udp6_hwcsum_outgoing. So no
need to test for ip_summed == CHECKSUM_PARTIAL first.

This revises an existing fix mentioned in the Fixes tag, which broke
small packets with GSO offload, as detected by kselftests.

Link: https://syzkaller.appspot.com/bug?extid=e1db31216c789f552871
Link: https://lore.kernel.org/netdev/20240723223109.2196886-1-kuba@kernel.org
Fixes: e269d79c7d ("net: missing check virtio")
Cc: stable@vger.kernel.org
Signed-off-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20240729201108.1615114-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

[5.15 stable: clean backport]
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-09-12 11:07:53 +02:00
..
acpi ACPI: utils: Fix acpi_evaluate_dsm_typed() redefinition error 2023-07-23 13:47:18 +02:00
asm-generic vmlinux.lds.h: catch .bss..L* sections into BSS") 2024-08-19 05:44:54 +02:00
clocksource
crypto crypto: af_alg - Disallow multiple in-flight AIO requests 2024-01-25 14:52:34 -08:00
drm drm/mipi-dsi: use correct return type for the DSC functions 2024-06-16 13:39:30 +02:00
dt-bindings dt-bindings: clocks: imx8mp: Add ID for usb suspend clock 2024-03-01 13:21:53 +01:00
keys KEYS: trusted: allow use of kernel RNG for key material 2023-10-19 23:05:33 +02:00
kunit
kvm KVM: arm64: vgic-v4: Make the doorbell request robust w.r.t preemption 2024-07-05 09:14:51 +02:00
linux net: drop bad gso csum_start and offset in virtio_net_hdr 2024-09-12 11:07:53 +02:00
math-emu
media media: cec: core: add adap_nb_transmit_canceled() callback 2024-06-16 13:39:53 +02:00
memory
misc
net Revert "Bluetooth: MGMT/SMP: Fix address type when using SMP over BREDR/LE" 2024-09-12 11:07:43 +02:00
pcmcia
ras
rdma RDMA/core: Fix umem iterator when PAGE_SIZE is greater then HCA pgsz 2023-12-13 18:36:40 +01:00
scsi scsi: core: Fix the return value of scsi_logical_block_count() 2024-09-04 13:23:35 +02:00
soc soc: qcom: rpmh-rsc: Enhance check for VRM in-flight request 2024-06-16 13:39:55 +02:00
sound ALSA: dmaengine: Synchronize dma channel after drop() 2024-07-27 10:46:11 +02:00
target scsi: target: Fix multiple LUN_RESET handling 2023-05-11 23:00:26 +09:00
trace mptcp: sched: check both directions for backup 2024-08-19 05:45:47 +02:00
uapi m68k: amiga: Turn off Warp1260 interrupts during boot 2024-08-19 05:45:13 +02:00
vdso
video
xen ACPI: processor: Fix evaluating _PDC method when running as Xen dom0 2023-05-11 23:00:22 +09:00