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Filename Latest commit message Latest commit date
j.nixdorf@avm.de 9588ac2edd net: ipv6: ensure we call ipv6_mc_down() at most once
commit 9995b408f17ff8c7f11bc725c8aa225ba3a63b1c upstream.

There are two reasons for addrconf_notify() to be called with NETDEV_DOWN:
either the network device is actually going down, or IPv6 was disabled
on the interface.

If either of them stays down while the other is toggled, we repeatedly
call the code for NETDEV_DOWN, including ipv6_mc_down(), while never
calling the corresponding ipv6_mc_up() in between. This will cause a
new entry in idev->mc_tomb to be allocated for each multicast group
the interface is subscribed to, which in turn leaks one struct ifmcaddr6
per nontrivial multicast group the interface is subscribed to.

The following reproducer will leak at least $n objects:

ip addr add ff2e::4242/32 dev eth0 autojoin
sysctl -w net.ipv6.conf.eth0.disable_ipv6=1
for i in $(seq 1 $n); do
	ip link set up eth0; ip link set down eth0
done

Joining groups with IPV6_ADD_MEMBERSHIP (unprivileged) or setting the
sysctl net.ipv6.conf.eth0.forwarding to 1 (=> subscribing to ff02::2)
can also be used to create a nontrivial idev->mc_list, which will the
leak objects with the right up-down-sequence.

Based on both sources for NETDEV_DOWN events the interface IPv6 state
should be considered:

 - not ready if the network interface is not ready OR IPv6 is disabled
   for it
 - ready if the network interface is ready AND IPv6 is enabled for it

The functions ipv6_mc_up() and ipv6_down() should only be run when this
state changes.

Implement this by remembering when the IPv6 state is ready, and only
run ipv6_mc_down() if it actually changed from ready to not ready.

The other direction (not ready -> ready) already works correctly, as:

 - the interface notification triggered codepath for NETDEV_UP /
   NETDEV_CHANGE returns early if ipv6 is disabled, and
 - the disable_ipv6=0 triggered codepath skips fully initializing the
   interface as long as addrconf_link_ready(dev) returns false
 - calling ipv6_mc_up() repeatedly does not leak anything

Fixes: 3ce62a84d5 ("ipv6: exit early in addrconf_notify() if IPv6 is disabled")
Signed-off-by: Johannes Nixdorf <j.nixdorf@avm.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
[jnixdorf: context updated for bpo to v4.19/v5.4]
Signed-off-by: Johannes Nixdorf <j.nixdorf@avm.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-05-12 12:23:48 +02:00
arch KVM: LAPIC: Enable timer posted-interrupt only when mwait/hlt is advertised 2022-05-12 12:23:48 +02:00
block block/compat_ioctl: fix range check in BLKGETSIZE 2022-04-27 13:50:50 +02:00
certs
crypto crypto: authenc - Fix sleep in atomic context in decrypt_tail 2022-04-15 14:18:04 +02:00
Documentation ext4, doc: fix incorrect h_reserved size 2022-04-27 13:50:50 +02:00
drivers drm/amdkfd: Use drm_priv to pass VM from KFD to amdgpu 2022-05-12 12:23:47 +02:00
fs NFSv4: Don't invalidate inode attributes on delegation return 2022-05-12 12:23:47 +02:00
include mm, hugetlb: allow for "high" userspace addresses 2022-05-09 09:03:28 +02:00
init init/main.c: return 1 from handled __setup() functions 2022-04-15 14:18:35 +02:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-12-01 09:23:35 +01:00
kernel genirq: Synchronize interrupt thread startup 2022-05-12 12:23:41 +02:00
lib hex2bin: fix access beyond string end 2022-05-09 09:03:22 +02:00
LICENSES
mm mm, hugetlb: allow for "high" userspace addresses 2022-05-09 09:03:28 +02:00
net net: ipv6: ensure we call ipv6_mc_down() at most once 2022-05-12 12:23:48 +02:00
samples samples/kretprobes: Fix return value if register_kretprobe() failed 2021-11-17 09:48:39 +01:00
scripts gcc-plugins: latent_entropy: use /dev/urandom 2022-04-20 09:19:38 +02:00
security Fix incorrect type in assignment of ipv6 port for audit 2022-04-15 14:18:22 +02:00
sound ASoC: dmaengine: Restore NULL prepare_slave_config() callback 2022-05-12 12:23:44 +02:00
tools selftests: mirror_gre_bridge_1q: Avoid changing PVID while interface is operational 2022-05-12 12:23:46 +02:00
usr
virt KVM: Prevent module exit until all VMs are freed 2022-04-15 14:18:27 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
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Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.192 2022-05-09 09:03:28 +02:00
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.

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.