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Paolo Abeni b9d0cb7581 ipv6: route: purge exception on removal 
[ Upstream commit f5b51fe804 ]

When a netdevice is unregistered, we flush the relevant exception
via rt6_sync_down_dev() -> fib6_ifdown() -> fib6_del() -> fib6_del_route().

Finally, we end-up calling rt6_remove_exception(), where we release
the relevant dst, while we keep the references to the related fib6_info and
dev. Such references should be released later when the dst will be
destroyed.

There are a number of caches that can keep the exception around for an
unlimited amount of time - namely dst_cache, possibly even socket cache.
As a result device registration may hang, as demonstrated by this script:

ip netns add cl
ip netns add rt
ip netns add srv
ip netns exec rt sysctl -w net.ipv6.conf.all.forwarding=1

ip link add name cl_veth type veth peer name cl_rt_veth
ip link set dev cl_veth netns cl
ip -n cl link set dev cl_veth up
ip -n cl addr add dev cl_veth 2001::2/64
ip -n cl route add default via 2001::1

ip -n cl link add tunv6 type ip6tnl mode ip6ip6 local 2001::2 remote 2002::1 hoplimit 64 dev cl_veth
ip -n cl link set tunv6 up
ip -n cl addr add 2013::2/64 dev tunv6

ip link set dev cl_rt_veth netns rt
ip -n rt link set dev cl_rt_veth up
ip -n rt addr add dev cl_rt_veth 2001::1/64

ip link add name rt_srv_veth type veth peer name srv_veth
ip link set dev srv_veth netns srv
ip -n srv link set dev srv_veth up
ip -n srv addr add dev srv_veth 2002::1/64
ip -n srv route add default via 2002::2

ip -n srv link add tunv6 type ip6tnl mode ip6ip6 local 2002::1 remote 2001::2 hoplimit 64 dev srv_veth
ip -n srv link set tunv6 up
ip -n srv addr add 2013::1/64 dev tunv6

ip link set dev rt_srv_veth netns rt
ip -n rt link set dev rt_srv_veth up
ip -n rt addr add dev rt_srv_veth 2002::2/64

ip netns exec srv netserver & sleep 0.1
ip netns exec cl ping6 -c 4 2013::1
ip netns exec cl netperf -H 2013::1 -t TCP_STREAM -l 3 & sleep 1
ip -n rt link set dev rt_srv_veth mtu 1400
wait %2

ip -n cl link del cl_veth

This commit addresses the issue purging all the references held by the
exception at time, as we currently do for e.g. ipv6 pcpu dst entries.

v1 -> v2:
 - re-order the code to avoid accessing dst and net after dst_dev_put()

Fixes: 93531c6743 ("net/ipv6: separate handling of FIB entries from dst based routes")
Signed-off-by: Paolo Abeni <pabeni@redhat.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>
2019-03-19 13:12:40 +01:00
arch perf/x86/intel: Implement support for TSX Force Abort 2019-03-13 14:02:41 -07:00
block blk-iolatency: fix IO hang due to negative inflight counter 2019-03-13 14:02:38 -07:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto net: crypto set sk to NULL when af_alg_release. 2019-02-23 09:07:24 +01:00
Documentation dt-bindings: eeprom: at24: add "atmel,24c2048" compatible string 2019-02-20 10:25:35 +01:00
drivers mdio_bus: Fix use-after-free on device_register fails 2019-03-19 13:12:40 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs cifs: allow calling SMB2_xxx_free(NULL) 2019-03-13 14:02:40 -07:00
include drm: disable uncached DMA optimization for ARM and arm64 2019-03-13 14:02:40 -07:00
init kbuild: Disable LD_DEAD_CODE_DATA_ELIMINATION with ftrace & GCC <= 4.7 2019-01-22 21:40:34 +01:00
ipc ipc/shm.c: use ERR_CAST() for shm_lock() error return 2018-10-05 16:32:04 -07:00
kernel bpf: Fix syscall's stackmap lookup potential deadlock 2019-03-13 14:02:36 -07:00
lib lib/test_kmod.c: potential double free in error handling 2019-03-13 14:02:32 -07:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm, memory_hotplug: fix off-by-one in is_pageblock_removable 2019-03-13 14:02:32 -07:00
net ipv6: route: purge exception on removal 2019-03-19 13:12:40 +01:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-02-15 08:10:11 +01:00
scripts scripts/gdb: fix lx-version string output 2019-02-12 19:47:20 +01:00
security apparmor: Fix aa_label_build() error handling for failed merges 2019-03-13 14:02:32 -07:00
sound ASoC: imx-audmux: change snprintf to scnprintf for possible overflow 2019-03-05 17:58:47 +01:00
tools perf trace: Support multiple "vfs_getname" probes 2019-03-13 14:02:37 -07:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt kvm: fix kvm_ioctl_create_device() reference counting (CVE-2019-6974) 2019-02-12 19:47:25 +01:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.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 MAINTAINERS: Add Sasha as a stable branch maintainer 2018-12-01 09:37:25 +01:00
Makefile Linux 4.19.29 2019-03-13 14:02:41 -07:00
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.