[5.10,23/86] ip6_gre: Fix skb_under_panic in __gre6_xmit()

From: Peilin Ye <peilin.ye@bytedance.com>

From: Peilin Ye <peilin.ye@bytedance.com>

[ Upstream commit ab198e1d0dd8dc4bc7575fb50758e2cbd51e14e1 ]

Feng reported an skb_under_panic BUG triggered by running
test_ip6gretap() in tools/testing/selftests/bpf/test_tunnel.sh:

[   82.492551] skbuff: skb_under_panic: text:ffffffffb268bb8e len:403 put:12 head:ffff9997c5480000 data:ffff9997c547fff8 tail:0x18b end:0x2c0 dev:ip6gretap11
<...>
[   82.607380] Call Trace:
[   82.609389]  <TASK>
[   82.611136]  skb_push.cold.109+0x10/0x10
[   82.614289]  __gre6_xmit+0x41e/0x590
[   82.617169]  ip6gre_tunnel_xmit+0x344/0x3f0
[   82.620526]  dev_hard_start_xmit+0xf1/0x330
[   82.623882]  sch_direct_xmit+0xe4/0x250
[   82.626961]  __dev_queue_xmit+0x720/0xfe0
<...>
[   82.633431]  packet_sendmsg+0x96a/0x1cb0
[   82.636568]  sock_sendmsg+0x30/0x40
<...>

The following sequence of events caused the BUG:

1. During ip6gretap device initialization, tunnel->tun_hlen (e.g. 4) is
   calculated based on old flags (see ip6gre_calc_hlen());
2. packet_snd() reserves header room for skb A, assuming
   tunnel->tun_hlen is 4;
3. Later (in clsact Qdisc), the eBPF program sets a new tunnel key for
   skb A using bpf_skb_set_tunnel_key() (see _ip6gretap_set_tunnel());
4. __gre6_xmit() detects the new tunnel key, and recalculates
   "tun_hlen" (e.g. 12) based on new flags (e.g. TUNNEL_KEY and
   TUNNEL_SEQ);
5. gre_build_header() calls skb_push() with insufficient reserved header
   room, triggering the BUG.

As sugguested by Cong, fix it by moving the call to skb_cow_head() after
the recalculation of tun_hlen.

Reproducer:

  OBJ=$LINUX/tools/testing/selftests/bpf/test_tunnel_kern.o

  ip netns add at_ns0
  ip link add veth0 type veth peer name veth1
  ip link set veth0 netns at_ns0
  ip netns exec at_ns0 ip addr add 172.16.1.100/24 dev veth0
  ip netns exec at_ns0 ip link set dev veth0 up
  ip link set dev veth1 up mtu 1500
  ip addr add dev veth1 172.16.1.200/24

  ip netns exec at_ns0 ip addr add ::11/96 dev veth0
  ip netns exec at_ns0 ip link set dev veth0 up
  ip addr add dev veth1 ::22/96
  ip link set dev veth1 up

  ip netns exec at_ns0 \
  	ip link add dev ip6gretap00 type ip6gretap seq flowlabel 0xbcdef key 2 \
  	local ::11 remote ::22

  ip netns exec at_ns0 ip addr add dev ip6gretap00 10.1.1.100/24
  ip netns exec at_ns0 ip addr add dev ip6gretap00 fc80::100/96
  ip netns exec at_ns0 ip link set dev ip6gretap00 up

  ip link add dev ip6gretap11 type ip6gretap external
  ip addr add dev ip6gretap11 10.1.1.200/24
  ip addr add dev ip6gretap11 fc80::200/24
  ip link set dev ip6gretap11 up

  tc qdisc add dev ip6gretap11 clsact
  tc filter add dev ip6gretap11 egress bpf da obj $OBJ sec ip6gretap_set_tunnel
  tc filter add dev ip6gretap11 ingress bpf da obj $OBJ sec ip6gretap_get_tunnel

  ping6 -c 3 -w 10 -q ::11

Fixes: 6712abc168eb ("ip6_gre: add ip6 gre and gretap collect_md mode")
Reported-by: Feng Zhou <zhoufeng.zf@bytedance.com>
Co-developed-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/ipv6/ip6_gre.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Message ID	20220426081741.880255898@linuxfoundation.org
State	Superseded
Headers	show Return-Path: <stable-owner@kernel.org> From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, stable@vger.kernel.org, Feng Zhou <zhoufeng.zf@bytedance.com>, Cong Wang <cong.wang@bytedance.com>, Peilin Ye <peilin.ye@bytedance.com>, "David S. Miller" <davem@davemloft.net>, Sasha Levin <sashal@kernel.org> Subject: [PATCH 5.10 23/86] ip6_gre: Fix skb_under_panic in __gre6_xmit() Date: Tue, 26 Apr 2022 10:20:51 +0200 Message-Id: <20220426081741.880255898@linuxfoundation.org> In-Reply-To: <20220426081741.202366502@linuxfoundation.org> References: <20220426081741.202366502@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	None \| expand [5.10,02/86] mm: page_alloc: fix building error on -Werror=array-compare [5.10,03/86] tracing: Dump stacktrace trigger to the corresponding instance [5.10,04/86] perf tools: Fix segfault accessing sample_id xyarray [5.10,05/86] gfs2: assign rgrp glock before compute_bitstructs [5.10,06/86] net/sched: cls_u32: fix netns refcount changes in u32_change() [5.10,07/86] ALSA: usb-audio: Clear MIDI port active flag after draining [5.10,08/86] ALSA: hda/realtek: Add quirk for Clevo NP70PNP [5.10,09/86] dm: fix mempool NULL pointer race when completing IO [5.10,10/86] ASoC: atmel: Remove system clock tree configuration for at91sam9g20ek [5.10,11/86] ASoC: msm8916-wcd-digital: Check failure for devm_snd_soc_register_component [5.10,12/86] ASoC: codecs: wcd934x: do not switch off SIDO Buck when codec is in use [5.10,13/86] dmaengine: imx-sdma: Fix error checking in sdma_event_remap [5.10,14/86] dmaengine: mediatek:Fix PM usage reference leak of mtk_uart_apdma_alloc_chan_resources [5.10,15/86] spi: spi-mtk-nor: initialize spi controller after resume [5.10,16/86] esp: limit skb_page_frag_refill use to a single page [5.10,17/86] igc: Fix infinite loop in release_swfw_sync [5.10,18/86] igc: Fix BUG: scheduling while atomic [5.10,19/86] rxrpc: Restore removed timer deletion [5.10,20/86] net/smc: Fix sock leak when release after smc_shutdown() [5.10,21/86] net/packet: fix packet_sock xmit return value checking [5.10,22/86] ip6_gre: Avoid updating tunnel->tun_hlen in __gre6_xmit() [5.10,23/86] ip6_gre: Fix skb_under_panic in __gre6_xmit() [5.10,24/86] net/sched: cls_u32: fix possible leak in u32_init_knode() [5.10,25/86] l3mdev: l3mdev_master_upper_ifindex_by_index_rcu should be using netdev_master_upper... [5.10,26/86] ipv6: make ip6_rt_gc_expire an atomic_t [5.10,27/86] netlink: reset network and mac headers in netlink_dump() [5.10,28/86] net: stmmac: Use readl_poll_timeout_atomic() in atomic state [5.10,29/86] dmaengine: idxd: add RO check for wq max_batch_size write [5.10,30/86] dmaengine: idxd: add RO check for wq max_transfer_size write [5.10,31/86] selftests: mlxsw: vxlan_flooding: Prevent flooding of unwanted packets [5.10,32/86] arm64/mm: Remove [PUD\|PMD]_TABLE_BIT from [pud\|pmd]_bad() [5.10,33/86] arm64: mm: fix p?d_leaf() [5.10,34/86] ARM: vexpress/spc: Avoid negative array index when !SMP [5.10,35/86] reset: tegra-bpmp: Restore Handle errors in BPMP response [5.10,36/86] platform/x86: samsung-laptop: Fix an unsigned comparison which can never be negative [5.10,37/86] ALSA: usb-audio: Fix undefined behavior due to shift overflowing the constant [5.10,38/86] arm64: dts: imx: Fix imx8*-var-som touchscreen property sizes [5.10,39/86] vxlan: fix error return code in vxlan_fdb_append [5.10,40/86] cifs: Check the IOCB_DIRECT flag, not O_DIRECT [5.10,41/86] net: atlantic: Avoid out-of-bounds indexing [5.10,42/86] mt76: Fix undefined behavior due to shift overflowing the constant [5.10,43/86] brcmfmac: sdio: Fix undefined behavior due to shift overflowing the constant [5.10,44/86] dpaa_eth: Fix missing of_node_put in dpaa_get_ts_info() [5.10,45/86] drm/msm/mdp5: check the return of kzalloc() [5.10,46/86] net: macb: Restart tx only if queue pointer is lagging [5.10,47/86] scsi: qedi: Fix failed disconnect handling [5.10,48/86] stat: fix inconsistency between struct stat and struct compat_stat [5.10,49/86] nvme: add a quirk to disable namespace identifiers [5.10,50/86] nvme-pci: disable namespace identifiers for Qemu controllers [5.10,51/86] EDAC/synopsys: Read the error count from the correct register [5.10,52/86] mm, hugetlb: allow for "high" userspace addresses [5.10,53/86] oom_kill.c: futex: delay the OOM reaper to allow time for proper futex cleanup [5.10,54/86] mm/mmu_notifier.c: fix race in mmu_interval_notifier_remove() [5.10,55/86] ata: pata_marvell: Check the bmdma_addr beforing reading [5.10,56/86] dma: at_xdmac: fix a missing check on list iterator [5.10,57/86] net: atlantic: invert deep par in pm functions, preventing null derefs [5.10,58/86] xtensa: patch_text: Fixup last cpu should be master [5.10,59/86] xtensa: fix a7 clobbering in coprocessor context load/store [5.10,60/86] openvswitch: fix OOB access in reserve_sfa_size() [5.10,61/86] gpio: Request interrupts after IRQ is initialized [5.10,62/86] ASoC: soc-dapm: fix two incorrect uses of list iterator [5.10,63/86] e1000e: Fix possible overflow in LTR decoding [5.10,64/86] ARC: entry: fix syscall_trace_exit argument [5.10,65/86] arm_pmu: Validate single/group leader events [5.10,66/86] sched/pelt: Fix attach_entity_load_avg() corner case [5.10,67/86] perf/core: Fix perf_mmap fail when CONFIG_PERF_USE_VMALLOC enabled [5.10,68/86] drm/panel/raspberrypi-touchscreen: Avoid NULL deref if not initialised [5.10,69/86] drm/panel/raspberrypi-touchscreen: Initialise the bridge in prepare [5.10,70/86] KVM: PPC: Fix TCE handling for VFIO [5.10,71/86] drm/vc4: Use pm_runtime_resume_and_get to fix pm_runtime_get_sync() usage [5.10,72/86] powerpc/perf: Fix power9 event alternatives [5.10,73/86] perf report: Set PERF_SAMPLE_DATA_SRC bit for Arm SPE event [5.10,74/86] ext4: fix fallocate to use file_modified to update permissions consistently [5.10,75/86] ext4: fix symlink file size not match to file content [5.10,76/86] ext4: fix use-after-free in ext4_search_dir [5.10,77/86] ext4: limit length to bitmap_maxbytes - blocksize in punch_hole [5.10,78/86] ext4, doc: fix incorrect h_reserved size [5.10,79/86] ext4: fix overhead calculation to account for the reserved gdt blocks [5.10,80/86] ext4: force overhead calculation if the s_overhead_cluster makes no sense [5.10,81/86] can: isotp: stop timeout monitoring when no first frame was sent [5.10,82/86] jbd2: fix a potential race while discarding reserved buffers after an abort [5.10,83/86] spi: atmel-quadspi: Fix the buswidth adjustment between spi-mem and controller [5.10,84/86] staging: ion: Prevent incorrect reference counting behavour [5.10,85/86] block/compat_ioctl: fix range check in BLKGETSIZE [5.10,86/86] Revert "net: micrel: fix KS8851_MLL Kconfig"

[5.10,23/86] ip6_gre: Fix skb_under_panic in __gre6_xmit()

Commit Message

Patch