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Eric Dumazet 9cb7c01342 ipv6: make ip6_rt_gc_expire an atomic_t
Reads and Writes to ip6_rt_gc_expire always have been racy,
as syzbot reported lately [1]

There is a possible risk of under-flow, leading
to unexpected high value passed to fib6_run_gc(),
although I have not observed this in the field.

Hosts hitting ip6_dst_gc() very hard are under pretty bad
state anyway.

[1]
BUG: KCSAN: data-race in ip6_dst_gc / ip6_dst_gc

read-write to 0xffff888102110744 of 4 bytes by task 13165 on cpu 1:
 ip6_dst_gc+0x1f3/0x220 net/ipv6/route.c:3311
 dst_alloc+0x9b/0x160 net/core/dst.c:86
 ip6_dst_alloc net/ipv6/route.c:344 [inline]
 icmp6_dst_alloc+0xb2/0x360 net/ipv6/route.c:3261
 mld_sendpack+0x2b9/0x580 net/ipv6/mcast.c:1807
 mld_send_cr net/ipv6/mcast.c:2119 [inline]
 mld_ifc_work+0x576/0x800 net/ipv6/mcast.c:2651
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

read-write to 0xffff888102110744 of 4 bytes by task 11607 on cpu 0:
 ip6_dst_gc+0x1f3/0x220 net/ipv6/route.c:3311
 dst_alloc+0x9b/0x160 net/core/dst.c:86
 ip6_dst_alloc net/ipv6/route.c:344 [inline]
 icmp6_dst_alloc+0xb2/0x360 net/ipv6/route.c:3261
 mld_sendpack+0x2b9/0x580 net/ipv6/mcast.c:1807
 mld_send_cr net/ipv6/mcast.c:2119 [inline]
 mld_ifc_work+0x576/0x800 net/ipv6/mcast.c:2651
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

value changed: 0x00000bb3 -> 0x00000ba9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11607 Comm: kworker/0:21 Not tainted 5.18.0-rc1-syzkaller-00037-g42e7a03d3bad-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: mld mld_ifc_work

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20220413181333.649424-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-04-15 14:28:50 -07:00
arch x86: 2022-04-12 14:16:33 -10:00
block for-5.18/block-2022-04-01 2022-04-01 16:20:00 -07:00
certs Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
crypto for-5.18/64bit-pi-2022-03-25 2022-03-26 12:01:35 -07:00
Documentation Networking fixes for 5.18-rc3, including fixes from wireless and 2022-04-14 11:58:19 -07:00
drivers net: Handle l3mdev in ip_tunnel_init_flow 2022-04-15 14:27:30 -07:00
fs for-5.18-rc2-tag 2022-04-14 10:58:27 -07:00
include ipv6: make ip6_rt_gc_expire an atomic_t 2022-04-15 14:28:50 -07:00
init Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
ipc fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
kernel - A couple of fixes to cgroup-related handling of perf events 2022-04-10 07:08:22 -10:00
lib Driver core changes for 5.18-rc2 2022-04-10 09:55:09 -10:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm - Allow the compiler to optimize away unused percpu accesses and change 2022-04-10 06:56:46 -10:00
net ipv6: make ip6_rt_gc_expire an atomic_t 2022-04-15 14:28:50 -07:00
samples dma-mapping updates for Linux 5.18 2022-03-29 08:50:14 -07:00
scripts hardening fixes for v5.18-rc3 2022-04-12 14:29:40 -10:00
security hardening updates for v5.18-rc1-fix1 2022-03-31 11:43:01 -07:00
sound sound fixes for 5.18-rc3 2022-04-14 11:08:12 -07:00
tools x86: 2022-04-12 14:16:33 -10:00
usr Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
virt KVM/arm64 fixes for 5.18, take #1 2022-04-08 12:30:04 -04:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update Vasily Averin's email address 2022-04-08 14:20:36 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS powerpc: Update MAINTAINERS for ibmvnic and VAS 2022-04-15 12:07:33 +01:00
Makefile Linux 5.18-rc2 2022-04-10 14:21:36 -10:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    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.