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Filename Latest commit message Latest commit date
Peilin Ye f185ede016 ip_gre, ip6_gre: Fix race condition on o_seqno in collect_md mode
[ Upstream commit 31c417c948d7f6909cb63f0ac3298f3c38f8ce20 ]

As pointed out by Jakub Kicinski, currently using TUNNEL_SEQ in
collect_md mode is racy for [IP6]GRE[TAP] devices.  Consider the
following sequence of events:

1. An [IP6]GRE[TAP] device is created in collect_md mode using "ip link
   add ... external".  "ip" ignores "[o]seq" if "external" is specified,
   so TUNNEL_SEQ is off, and the device is marked as NETIF_F_LLTX (i.e.
   it uses lockless TX);
2. Someone sets TUNNEL_SEQ on outgoing skb's, using e.g.
   bpf_skb_set_tunnel_key() in an eBPF program attached to this device;
3. gre_fb_xmit() or __gre6_xmit() processes these skb's:

	gre_build_header(skb, tun_hlen,
			 flags, protocol,
			 tunnel_id_to_key32(tun_info->key.tun_id),
			 (flags & TUNNEL_SEQ) ? htonl(tunnel->o_seqno++)
					      : 0);   ^^^^^^^^^^^^^^^^^

Since we are not using the TX lock (&txq->_xmit_lock), multiple CPUs may
try to do this tunnel->o_seqno++ in parallel, which is racy.  Fix it by
making o_seqno atomic_t.

As mentioned by Eric Dumazet in commit b790e01aee ("ip_gre: lockless
xmit"), making o_seqno atomic_t increases "chance for packets being out
of order at receiver" when NETIF_F_LLTX is on.

Maybe a better fix would be:

1. Do not ignore "oseq" in external mode.  Users MUST specify "oseq" if
   they want the kernel to allow sequencing of outgoing packets;
2. Reject all outgoing TUNNEL_SEQ packets if the device was not created
   with "oseq".

Unfortunately, that would break userspace.

We could now make [IP6]GRE[TAP] devices always NETIF_F_LLTX, but let us
do it in separate patches to keep this fix minimal.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Fixes: 77a5196a80 ("gre: add sequence number for collect md mode.")
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Acked-by: William Tu <u9012063@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: d80fc101d2eb ("erspan: get the proto with the md version for collect_md")
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-05-30 12:44:05 +01:00
arch ARM: 9296/1: HP Jornada 7XX: fix kernel-doc warnings 2023-05-30 12:44:01 +01:00
block blk-iocost: fix divide by 0 error in calc_lcoefs() 2023-03-11 16:43:54 +01:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:11:22 +02:00
crypto crypto: drbg - Only fail when jent is unavailable in FIPS mode 2023-05-17 11:35:42 +02:00
Documentation media: uapi: add MEDIA_BUS_FMT_METADATA_FIXED media bus format. 2023-05-17 11:35:36 +02:00
drivers serial: arc_uart: fix of_iomap leak in arc_serial_probe 2023-05-30 12:44:05 +01:00
fs btrfs: fix space cache inconsistency after error loading it from disk 2023-05-30 12:44:04 +01:00
include ip_gre, ip6_gre: Fix race condition on o_seqno in collect_md mode 2023-05-30 12:44:05 +01:00
init init/Kconfig: fix CC_HAS_ASM_GOTO_TIED_OUTPUT test with dash 2022-12-08 11:22:59 +01:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:23:06 +01:00
kernel relayfs: fix out-of-bounds access in relay_file_read 2023-05-17 11:35:58 +02:00
lib lib: cpu_rmap: Avoid use after free on rmap->obj array entries 2023-05-30 12:44:03 +01:00
LICENSES
mm mm/page_alloc: fix potential deadlock on zonelist_update_seq seqlock 2023-05-17 11:36:05 +02:00
net ip_gre, ip6_gre: Fix race condition on o_seqno in collect_md mode 2023-05-30 12:44:05 +01:00
samples samples/bpf: Fix fout leak in hbm's run_bpf_prog 2023-05-30 12:44:03 +01:00
scripts recordmcount: Fix memory leaks in the uwrite function 2023-05-30 12:44:04 +01:00
security selinux: ensure av_permissions.h is built when needed 2023-05-17 11:35:34 +02:00
sound ALSA: firewire-digi00x: prevent potential use after free 2023-05-30 12:44:05 +01:00
tools cpupower: Make TSC read per CPU for Mperf monitor 2023-05-30 12:44:04 +01:00
usr
virt KVM: Destroy target device if coalesced MMIO unregistration fails 2023-03-11 16:44:01 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS net/phy/mdio-i2c: Move header file to include/linux/mdio 2023-02-06 07:52:46 +01:00
Makefile Linux 5.4.243 2023-05-17 11:36:05 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.