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Eric Dumazet 26e398dcb3 ipv6: fixes rt6_probe() and fib6_nh->last_probe init [ Upstream commit `1bef4c223b` ] While looking at a syzbot KCSAN report [1], I found multiple issues in this code : 1) fib6_nh->last_probe has an initial value of 0. While probably okay on 64bit kernels, this causes an issue on 32bit kernels since the time_after(jiffies, 0 + interval) might be false ~24 days after boot (for HZ=1000) 2) The data-race found by KCSAN I could use READ_ONCE() and WRITE_ONCE(), but we also can take the opportunity of not piling-up too many rt6_probe_deferred() works by using instead cmpxchg() so that only one cpu wins the race. [1] BUG: KCSAN: data-race in find_match / find_match write to 0xffff8880bb7aabe8 of 8 bytes by interrupt on cpu 1: rt6_probe net/ipv6/route.c:663 [inline] find_match net/ipv6/route.c:757 [inline] find_match+0x5bd/0x790 net/ipv6/route.c:733 __find_rr_leaf+0xe3/0x780 net/ipv6/route.c:831 find_rr_leaf net/ipv6/route.c:852 [inline] rt6_select net/ipv6/route.c:896 [inline] fib6_table_lookup+0x383/0x650 net/ipv6/route.c:2164 ip6_pol_route+0xee/0x5c0 net/ipv6/route.c:2200 ip6_pol_route_output+0x48/0x60 net/ipv6/route.c:2452 fib6_rule_lookup+0x3d6/0x470 net/ipv6/fib6_rules.c:117 ip6_route_output_flags_noref+0x16b/0x230 net/ipv6/route.c:2484 ip6_route_output_flags+0x50/0x1a0 net/ipv6/route.c:2497 ip6_dst_lookup_tail+0x25d/0xc30 net/ipv6/ip6_output.c:1049 ip6_dst_lookup_flow+0x68/0x120 net/ipv6/ip6_output.c:1150 inet6_csk_route_socket+0x2f7/0x420 net/ipv6/inet6_connection_sock.c:106 inet6_csk_xmit+0x91/0x1f0 net/ipv6/inet6_connection_sock.c:121 __tcp_transmit_skb+0xe81/0x1d60 net/ipv4/tcp_output.c:1169 tcp_transmit_skb net/ipv4/tcp_output.c:1185 [inline] tcp_xmit_probe_skb+0x19b/0x1d0 net/ipv4/tcp_output.c:3735 read to 0xffff8880bb7aabe8 of 8 bytes by interrupt on cpu 0: rt6_probe net/ipv6/route.c:657 [inline] find_match net/ipv6/route.c:757 [inline] find_match+0x521/0x790 net/ipv6/route.c:733 __find_rr_leaf+0xe3/0x780 net/ipv6/route.c:831 find_rr_leaf net/ipv6/route.c:852 [inline] rt6_select net/ipv6/route.c:896 [inline] fib6_table_lookup+0x383/0x650 net/ipv6/route.c:2164 ip6_pol_route+0xee/0x5c0 net/ipv6/route.c:2200 ip6_pol_route_output+0x48/0x60 net/ipv6/route.c:2452 fib6_rule_lookup+0x3d6/0x470 net/ipv6/fib6_rules.c:117 ip6_route_output_flags_noref+0x16b/0x230 net/ipv6/route.c:2484 ip6_route_output_flags+0x50/0x1a0 net/ipv6/route.c:2497 ip6_dst_lookup_tail+0x25d/0xc30 net/ipv6/ip6_output.c:1049 ip6_dst_lookup_flow+0x68/0x120 net/ipv6/ip6_output.c:1150 inet6_csk_route_socket+0x2f7/0x420 net/ipv6/inet6_connection_sock.c:106 inet6_csk_xmit+0x91/0x1f0 net/ipv6/inet6_connection_sock.c:121 __tcp_transmit_skb+0xe81/0x1d60 net/ipv4/tcp_output.c:1169 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 18894 Comm: udevd Not tainted 5.4.0-rc3+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Fixes: `cc3a86c802` ("ipv6: Change rt6_probe to take a fib6_nh") Fixes: `f547fac624` ("ipv6: rate-limit probes for neighbourless routes") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Reviewed-by: David Ahern <dsahern@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2019-11-12 19:20:33 +01:00
arch	arm64: dts: ti: k3-am65-main: Fix gic-its node unit-address	2019-11-10 11:27:56 +01:00
block	blk-rq-qos: fix first node deletion of rq_qos_del()	2019-10-29 09:20:09 +01:00
certs	export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR()	2018-08-22 23:21:44 +09:00
crypto	crypto: skcipher - Unmap pages after an external error	2019-10-11 18:20:52 +02:00
Documentation	x86/xen: Return from panic notifier	2019-11-06 13:05:55 +01:00
drivers	net: mscc: ocelot: fix NULL pointer on LAG slave removal	2019-11-12 19:20:32 +01:00
firmware	kbuild: remove all dummy assignments to obj-	2017-11-18 11:46:06 +09:00
fs	cifs: Fix cifsInodeInfo lock_sem deadlock when reconnect occurs	2019-11-10 11:27:34 +01:00
include	net: fix data-race in neigh_event_send()	2019-11-12 19:20:28 +01:00
init	initramfs: don't free a non-existent initrd	2019-10-01 08:26:09 +02:00
ipc	ipc/mqueue.c: only perform resource calculation if user valid	2019-08-06 19:06:52 +02:00
kernel	tracing: Fix "gfp_t" format for synthetic events	2019-11-10 11:27:28 +01:00
lib	lib: textsearch: fix escapes in example code	2019-10-29 09:19:35 +01:00
LICENSES	LICENSES: Remove CC-BY-SA-4.0 license text	2018-10-18 11:28:50 +02:00
mm	mm/memory-failure: poison read receives SIGKILL instead of SIGBUS if mmaped more than once	2019-10-29 09:19:59 +01:00
net	ipv6: fixes rt6_probe() and fib6_nh->last_probe init	2019-11-12 19:20:33 +01:00
samples	samples: bpf: fix: seg fault with NULL pointer arg	2019-11-06 13:05:30 +01:00
scripts	scripts/setlocalversion: Improve -dirty check with git-status --no-optional-locks	2019-11-06 13:05:27 +01:00
security	ima: fix freeing ongoing ahash_request	2019-10-11 18:21:11 +02:00
sound	ASoC: pcm3168a: The codec does not support S32_LE	2019-11-10 11:27:56 +01:00
tools	selftests/powerpc: Fix compile error on tlbie_test due to newer gcc	2019-11-10 11:27:55 +01:00
usr	kbuild: clean compressed initramfs image	2019-10-07 18:57:16 +02:00
virt	KVM: coalesced_mmio: add bounds checking	2019-09-21 07:16:44 +02:00
.clang-format	clang-format: Set IndentWrappedFunctionNames false	2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore	Kbuild updates for v4.17 (2nd)	2018-04-15 17:21:30 -07:00
.mailmap	libnvdimm-for-4.19_misc	2018-08-25 18:13:10 -07:00
COPYING	COPYING: use the new text with points to the license files	2018-03-23 12:41:45 -06:00
CREDITS	9p: remove Ron Minnich from MAINTAINERS	2018-08-17 16:20:26 -07:00
Kbuild	Kbuild updates for v4.15	2017-11-17 17:45:29 -08:00
Kconfig	kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt	2018-08-02 08:06:55 +09:00
MAINTAINERS	USB: rio500: Remove Rio 500 kernel driver	2019-10-17 13:44:47 -07:00
Makefile	Linux 4.19.83	2019-11-10 11:27:57 +01:00
README	Docs: Added a pointer to the formatted docs to README	2018-03-21 09:02:53 -06:00

README

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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.