<feed xmlns='http://www.w3.org/2005/Atom'>
<title>user/sven/linux.git/include, branch v4.19.162</title>
<subtitle>Linux Kernel
</subtitle>
<id>https://git.stealer.net/cgit.cgi/user/sven/linux.git/atom?h=v4.19.162</id>
<link rel='self' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/atom?h=v4.19.162'/>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/'/>
<updated>2020-12-08T09:18:53Z</updated>
<entry>
<title>bonding: wait for sysfs kobject destruction before freeing struct slave</title>
<updated>2020-12-08T09:18:53Z</updated>
<author>
<name>Jamie Iles</name>
<email>jamie@nuviainc.com</email>
</author>
<published>2020-11-20T14:28:27Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=8285a15cd47d6607186e0e63d882f19d462f71bd'/>
<id>urn:sha1:8285a15cd47d6607186e0e63d882f19d462f71bd</id>
<content type='text'>
[ Upstream commit b9ad3e9f5a7a760ab068e33e1f18d240ba32ce92 ]

syzkaller found that with CONFIG_DEBUG_KOBJECT_RELEASE=y, releasing a
struct slave device could result in the following splat:

  kobject: 'bonding_slave' (00000000cecdd4fe): kobject_release, parent 0000000074ceb2b2 (delayed 1000)
  bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
  ------------[ cut here ]------------
  ODEBUG: free active (active state 0) object type: timer_list hint: workqueue_select_cpu_near kernel/workqueue.c:1549 [inline]
  ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x98 kernel/workqueue.c:1600
  WARNING: CPU: 1 PID: 842 at lib/debugobjects.c:485 debug_print_object+0x180/0x240 lib/debugobjects.c:485
  Kernel panic - not syncing: panic_on_warn set ...
  CPU: 1 PID: 842 Comm: kworker/u4:4 Tainted: G S                5.9.0-rc8+ #96
  Hardware name: linux,dummy-virt (DT)
  Workqueue: netns cleanup_net
  Call trace:
   dump_backtrace+0x0/0x4d8 include/linux/bitmap.h:239
   show_stack+0x34/0x48 arch/arm64/kernel/traps.c:142
   __dump_stack lib/dump_stack.c:77 [inline]
   dump_stack+0x174/0x1f8 lib/dump_stack.c:118
   panic+0x360/0x7a0 kernel/panic.c:231
   __warn+0x244/0x2ec kernel/panic.c:600
   report_bug+0x240/0x398 lib/bug.c:198
   bug_handler+0x50/0xc0 arch/arm64/kernel/traps.c:974
   call_break_hook+0x160/0x1d8 arch/arm64/kernel/debug-monitors.c:322
   brk_handler+0x30/0xc0 arch/arm64/kernel/debug-monitors.c:329
   do_debug_exception+0x184/0x340 arch/arm64/mm/fault.c:864
   el1_dbg+0x48/0xb0 arch/arm64/kernel/entry-common.c:65
   el1_sync_handler+0x170/0x1c8 arch/arm64/kernel/entry-common.c:93
   el1_sync+0x80/0x100 arch/arm64/kernel/entry.S:594
   debug_print_object+0x180/0x240 lib/debugobjects.c:485
   __debug_check_no_obj_freed lib/debugobjects.c:967 [inline]
   debug_check_no_obj_freed+0x200/0x430 lib/debugobjects.c:998
   slab_free_hook mm/slub.c:1536 [inline]
   slab_free_freelist_hook+0x190/0x210 mm/slub.c:1577
   slab_free mm/slub.c:3138 [inline]
   kfree+0x13c/0x460 mm/slub.c:4119
   bond_free_slave+0x8c/0xf8 drivers/net/bonding/bond_main.c:1492
   __bond_release_one+0xe0c/0xec8 drivers/net/bonding/bond_main.c:2190
   bond_slave_netdev_event drivers/net/bonding/bond_main.c:3309 [inline]
   bond_netdev_event+0x8f0/0xa70 drivers/net/bonding/bond_main.c:3420
   notifier_call_chain+0xf0/0x200 kernel/notifier.c:83
   __raw_notifier_call_chain kernel/notifier.c:361 [inline]
   raw_notifier_call_chain+0x44/0x58 kernel/notifier.c:368
   call_netdevice_notifiers_info+0xbc/0x150 net/core/dev.c:2033
   call_netdevice_notifiers_extack net/core/dev.c:2045 [inline]
   call_netdevice_notifiers net/core/dev.c:2059 [inline]
   rollback_registered_many+0x6a4/0xec0 net/core/dev.c:9347
   unregister_netdevice_many.part.0+0x2c/0x1c0 net/core/dev.c:10509
   unregister_netdevice_many net/core/dev.c:10508 [inline]
   default_device_exit_batch+0x294/0x338 net/core/dev.c:10992
   ops_exit_list.isra.0+0xec/0x150 net/core/net_namespace.c:189
   cleanup_net+0x44c/0x888 net/core/net_namespace.c:603
   process_one_work+0x96c/0x18c0 kernel/workqueue.c:2269
   worker_thread+0x3f0/0xc30 kernel/workqueue.c:2415
   kthread+0x390/0x498 kernel/kthread.c:292
   ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:925

This is a potential use-after-free if the sysfs nodes are being accessed
whilst removing the struct slave, so wait for the object destruction to
complete before freeing the struct slave itself.

Fixes: 07699f9a7c8d ("bonding: add sysfs /slave dir for bond slave devices.")
Fixes: a068aab42258 ("bonding: Fix reference count leak in bond_sysfs_slave_add.")
Cc: Qiushi Wu &lt;wu000273@umn.edu&gt;
Cc: Jay Vosburgh &lt;j.vosburgh@gmail.com&gt;
Cc: Veaceslav Falico &lt;vfalico@gmail.com&gt;
Cc: Andy Gospodarek &lt;andy@greyhouse.net&gt;
Signed-off-by: Jamie Iles &lt;jamie@nuviainc.com&gt;
Reviewed-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Link: https://lore.kernel.org/r/20201120142827.879226-1-jamie@nuviainc.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net/tls: Protect from calling tls_dev_del for TLS RX twice</title>
<updated>2020-12-08T09:18:52Z</updated>
<author>
<name>Maxim Mikityanskiy</name>
<email>maximmi@mellanox.com</email>
</author>
<published>2020-11-25T22:18:10Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=2ba413da624ee45b29cc9de5fff710c19c4efcde'/>
<id>urn:sha1:2ba413da624ee45b29cc9de5fff710c19c4efcde</id>
<content type='text'>
[ Upstream commit 025cc2fb6a4e84e9a0552c0017dcd1c24b7ac7da ]

tls_device_offload_cleanup_rx doesn't clear tls_ctx-&gt;netdev after
calling tls_dev_del if TLX TX offload is also enabled. Clearing
tls_ctx-&gt;netdev gets postponed until tls_device_gc_task. It leaves a
time frame when tls_device_down may get called and call tls_dev_del for
RX one extra time, confusing the driver, which may lead to a crash.

This patch corrects this racy behavior by adding a flag to prevent
tls_device_down from calling tls_dev_del the second time.

Fixes: e8f69799810c ("net/tls: Add generic NIC offload infrastructure")
Signed-off-by: Maxim Mikityanskiy &lt;maximmi@mellanox.com&gt;
Signed-off-by: Saeed Mahameed &lt;saeedm@nvidia.com&gt;
Link: https://lore.kernel.org/r/20201125221810.69870-1-saeedm@nvidia.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>scsi: libiscsi: Fix NOP race condition</title>
<updated>2020-12-02T07:48:09Z</updated>
<author>
<name>Lee Duncan</name>
<email>lduncan@suse.com</email>
</author>
<published>2020-11-06T19:33:17Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=e0172455d4e9e946a2d388386ec48dd7538275ec'/>
<id>urn:sha1:e0172455d4e9e946a2d388386ec48dd7538275ec</id>
<content type='text'>
[ Upstream commit fe0a8a95e7134d0b44cd407bc0085b9ba8d8fe31 ]

iSCSI NOPs are sometimes "lost", mistakenly sent to the user-land iscsid
daemon instead of handled in the kernel, as they should be, resulting in a
message from the daemon like:

  iscsid: Got nop in, but kernel supports nop handling.

This can occur because of the new forward- and back-locks, and the fact
that an iSCSI NOP response can occur before processing of the NOP send is
complete. This can result in "conn-&gt;ping_task" being NULL in
iscsi_nop_out_rsp(), when the pointer is actually in the process of being
set.

To work around this, we add a new state to the "ping_task" pointer. In
addition to NULL (not assigned) and a pointer (assigned), we add the state
"being set", which is signaled with an INVALID pointer (using "-1").

Link: https://lore.kernel.org/r/20201106193317.16993-1-leeman.duncan@gmail.com
Reviewed-by: Mike Christie &lt;michael.christie@oracle.com&gt;
Signed-off-by: Lee Duncan &lt;lduncan@suse.com&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>drm/atomic_helper: Stop modesets on unregistered connectors harder</title>
<updated>2020-12-02T07:48:08Z</updated>
<author>
<name>Lyude Paul</name>
<email>lyude@redhat.com</email>
</author>
<published>2018-10-16T20:39:46Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=72289dc23c3c6311d21d87eee55278aa4308a73e'/>
<id>urn:sha1:72289dc23c3c6311d21d87eee55278aa4308a73e</id>
<content type='text'>
commit de9f8eea5a44b0b756d3d6345af7f8e630a3c8c0 upstream.

Unfortunately, it appears our fix in:
commit b5d29843d8ef ("drm/atomic_helper: Allow DPMS On&lt;-&gt;Off changes
for unregistered connectors")

Which attempted to work around the problems introduced by:
commit 4d80273976bf ("drm/atomic_helper: Disallow new modesets on
unregistered connectors")

Is still not the right solution, as modesets can still be triggered
outside of drm_atomic_set_crtc_for_connector().

So in order to fix this, while still being careful that we don't break
modesets that a driver may perform before being registered with
userspace, we replace connector-&gt;registered with a tristate member,
connector-&gt;registration_state. This allows us to keep track of whether
or not a connector is still initializing and hasn't been exposed to
userspace, is currently registered and exposed to userspace, or has been
legitimately removed from the system after having once been present.

Using this info, we can prevent userspace from performing new modesets
on unregistered connectors while still allowing the driver to perform
modesets on unregistered connectors before the driver has finished being
registered.

Changes since v1:
- Fix WARN_ON() in drm_connector_cleanup() that CI caught with this
  patchset in igt@drv_module_reload@basic-reload-inject and
  igt@drv_module_reload@basic-reload by checking if the connector is
  registered instead of unregistered, as calling drm_connector_cleanup()
  on a connector that hasn't been registered with userspace yet should
  stay valid.
- Remove unregistered_connector_check(), and just go back to what we
  were doing before in commit 4d80273976bf ("drm/atomic_helper: Disallow
  new modesets on unregistered connectors") except replacing
  READ_ONCE(connector-&gt;registered) with drm_connector_is_unregistered().
  This gets rid of the behavior of allowing DPMS On&lt;-&gt;Off, but that should
  be fine as it's more consistent with the UAPI we had before - danvet
- s/drm_connector_unregistered/drm_connector_is_unregistered/ - danvet
- Update documentation, fix some typos.

Fixes: b5d29843d8ef ("drm/atomic_helper: Allow DPMS On&lt;-&gt;Off changes for unregistered connectors")
Cc: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Cc: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Cc: Rodrigo Vivi &lt;rodrigo.vivi@intel.com&gt;
Cc: stable@vger.kernel.org
Cc: David Airlie &lt;airlied@linux.ie&gt;
Signed-off-by: Lyude Paul &lt;lyude@redhat.com&gt;
Reviewed-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20181016203946.9601-1-lyude@redhat.com
(cherry picked from commit 39b50c603878f4f8ae541ac4088a805d588abc79)
Fixes: e96550956fbc ("drm/atomic_helper: Disallow new modesets on unregistered connectors")
Fixes: 34ca26a98ad6 ("drm/atomic_helper: Allow DPMS On&lt;-&gt;Off changes for unregistered connectors")
Cc: stable@vger.kernel.org
Signed-off-by: Joonas Lahtinen &lt;joonas.lahtinen@linux.intel.com&gt;
Cc: Christoph Niedermaier &lt;cniedermaier@dh-electronics.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;


</content>
</entry>
<entry>
<title>wireless: Use linux/stddef.h instead of stddef.h</title>
<updated>2020-12-02T07:48:07Z</updated>
<author>
<name>Hauke Mehrtens</name>
<email>hauke@hauke-m.de</email>
</author>
<published>2020-05-21T20:14:22Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=a6b9a7f781b88f1a1ddba93b504206d86bfbf68e'/>
<id>urn:sha1:a6b9a7f781b88f1a1ddba93b504206d86bfbf68e</id>
<content type='text'>
commit 1b9ae0c92925ac40489be526d67d0010d0724ce0 upstream.

When compiling inside the kernel include linux/stddef.h instead of
stddef.h. When I compile this header file in backports for power PC I
run into a conflict with ptrdiff_t. I was unable to reproduce this in
mainline kernel. I still would like to fix this problem in the kernel.

Fixes: 6989310f5d43 ("wireless: Use offsetof instead of custom macro.")
Signed-off-by: Hauke Mehrtens &lt;hauke@hauke-m.de&gt;
Link: https://lore.kernel.org/r/20200521201422.16493-1-hauke@hauke-m.de
Signed-off-by: Johannes Berg &lt;johannes.berg@intel.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>netfilter: clear skb-&gt;next in NF_HOOK_LIST()</title>
<updated>2020-12-02T07:48:07Z</updated>
<author>
<name>Cong Wang</name>
<email>cong.wang@bytedance.com</email>
</author>
<published>2020-11-21T03:43:17Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=5460d62d661c0fc53bfe83493821b1dc3dc969f4'/>
<id>urn:sha1:5460d62d661c0fc53bfe83493821b1dc3dc969f4</id>
<content type='text'>
NF_HOOK_LIST() uses list_del() to remove skb from the linked list,
however, it is not sufficient as skb-&gt;next still points to other
skb. We should just call skb_list_del_init() to clear skb-&gt;next,
like the rest places which using skb list.

This has been fixed in upstream by commit ca58fbe06c54
("netfilter: add and use nf_hook_slow_list()").

Fixes: 9f17dbf04ddf ("netfilter: fix use-after-free in NF_HOOK_LIST")
Reported-by: liuzx@knownsec.com
Tested-by: liuzx@knownsec.com
Cc: Florian Westphal &lt;fw@strlen.de&gt;
Cc: Edward Cree &lt;ecree@solarflare.com&gt;
Cc: stable@vger.kernel.org # between 4.19 and 5.4
Signed-off-by: Cong Wang &lt;cong.wang@bytedance.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>ip_tunnels: Set tunnel option flag when tunnel metadata is present</title>
<updated>2020-11-24T12:27:21Z</updated>
<author>
<name>Yi-Hung Wei</name>
<email>yihung.wei@gmail.com</email>
</author>
<published>2020-11-11T00:16:40Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=901e04cd478133ba6458fecbd3b232b528d26f3b'/>
<id>urn:sha1:901e04cd478133ba6458fecbd3b232b528d26f3b</id>
<content type='text'>
[ Upstream commit 9c2e14b48119b39446031d29d994044ae958d8fc ]

Currently, we may set the tunnel option flag when the size of metadata
is zero.  For example, we set TUNNEL_GENEVE_OPT in the receive function
no matter the geneve option is present or not.  As this may result in
issues on the tunnel flags consumers, this patch fixes the issue.

Related discussion:
* https://lore.kernel.org/netdev/1604448694-19351-1-git-send-email-yihung.wei@gmail.com/T/#u

Fixes: 256c87c17c53 ("net: check tunnel option type in tunnel flags")
Signed-off-by: Yi-Hung Wei &lt;yihung.wei@gmail.com&gt;
Link: https://lore.kernel.org/r/1605053800-74072-1-git-send-email-yihung.wei@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>random32: make prandom_u32() output unpredictable</title>
<updated>2020-11-18T18:18:52Z</updated>
<author>
<name>George Spelvin</name>
<email>lkml@sdf.org</email>
</author>
<published>2020-08-09T06:57:44Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=81d7c56d6fab5ccbf522c47a655cd427808679f2'/>
<id>urn:sha1:81d7c56d6fab5ccbf522c47a655cd427808679f2</id>
<content type='text'>
commit c51f8f88d705e06bd696d7510aff22b33eb8e638 upstream.

Non-cryptographic PRNGs may have great statistical properties, but
are usually trivially predictable to someone who knows the algorithm,
given a small sample of their output.  An LFSR like prandom_u32() is
particularly simple, even if the sample is widely scattered bits.

It turns out the network stack uses prandom_u32() for some things like
random port numbers which it would prefer are *not* trivially predictable.
Predictability led to a practical DNS spoofing attack.  Oops.

This patch replaces the LFSR with a homebrew cryptographic PRNG based
on the SipHash round function, which is in turn seeded with 128 bits
of strong random key.  (The authors of SipHash have *not* been consulted
about this abuse of their algorithm.)  Speed is prioritized over security;
attacks are rare, while performance is always wanted.

Replacing all callers of prandom_u32() is the quick fix.
Whether to reinstate a weaker PRNG for uses which can tolerate it
is an open question.

Commit f227e3ec3b5c ("random32: update the net random state on interrupt
and activity") was an earlier attempt at a solution.  This patch replaces
it.

Reported-by: Amit Klein &lt;aksecurity@gmail.com&gt;
Cc: Willy Tarreau &lt;w@1wt.eu&gt;
Cc: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: "Jason A. Donenfeld" &lt;Jason@zx2c4.com&gt;
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: tytso@mit.edu
Cc: Florian Westphal &lt;fw@strlen.de&gt;
Cc: Marc Plumb &lt;lkml.mplumb@gmail.com&gt;
Fixes: f227e3ec3b5c ("random32: update the net random state on interrupt and activity")
Signed-off-by: George Spelvin &lt;lkml@sdf.org&gt;
Link: https://lore.kernel.org/netdev/20200808152628.GA27941@SDF.ORG/
[ willy: partial reversal of f227e3ec3b5c; moved SIPROUND definitions
  to prandom.h for later use; merged George's prandom_seed() proposal;
  inlined siprand_u32(); replaced the net_rand_state[] array with 4
  members to fix a build issue; cosmetic cleanups to make checkpatch
  happy; fixed RANDOM32_SELFTEST build ]
[wt: backported to 4.19 -- various context adjustments]
Signed-off-by: Willy Tarreau &lt;w@1wt.eu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>netfilter: use actual socket sk rather than skb sk when routing harder</title>
<updated>2020-11-18T18:18:44Z</updated>
<author>
<name>Jason A. Donenfeld</name>
<email>Jason@zx2c4.com</email>
</author>
<published>2020-10-29T02:56:06Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=580a117919f3ae1390be6b4111253ee9595938f5'/>
<id>urn:sha1:580a117919f3ae1390be6b4111253ee9595938f5</id>
<content type='text'>
commit 46d6c5ae953cc0be38efd0e469284df7c4328cf8 upstream.

If netfilter changes the packet mark when mangling, the packet is
rerouted using the route_me_harder set of functions. Prior to this
commit, there's one big difference between route_me_harder and the
ordinary initial routing functions, described in the comment above
__ip_queue_xmit():

   /* Note: skb-&gt;sk can be different from sk, in case of tunnels */
   int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,

That function goes on to correctly make use of sk-&gt;sk_bound_dev_if,
rather than skb-&gt;sk-&gt;sk_bound_dev_if. And indeed the comment is true: a
tunnel will receive a packet in ndo_start_xmit with an initial skb-&gt;sk.
It will make some transformations to that packet, and then it will send
the encapsulated packet out of a *new* socket. That new socket will
basically always have a different sk_bound_dev_if (otherwise there'd be
a routing loop). So for the purposes of routing the encapsulated packet,
the routing information as it pertains to the socket should come from
that socket's sk, rather than the packet's original skb-&gt;sk. For that
reason __ip_queue_xmit() and related functions all do the right thing.

One might argue that all tunnels should just call skb_orphan(skb) before
transmitting the encapsulated packet into the new socket. But tunnels do
*not* do this -- and this is wisely avoided in skb_scrub_packet() too --
because features like TSQ rely on skb-&gt;destructor() being called when
that buffer space is truely available again. Calling skb_orphan(skb) too
early would result in buffers filling up unnecessarily and accounting
info being all wrong. Instead, additional routing must take into account
the new sk, just as __ip_queue_xmit() notes.

So, this commit addresses the problem by fishing the correct sk out of
state-&gt;sk -- it's already set properly in the call to nf_hook() in
__ip_local_out(), which receives the sk as part of its normal
functionality. So we make sure to plumb state-&gt;sk through the various
route_me_harder functions, and then make correct use of it following the
example of __ip_queue_xmit().

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jason A. Donenfeld &lt;Jason@zx2c4.com&gt;
Reviewed-by: Florian Westphal &lt;fw@strlen.de&gt;
Signed-off-by: Pablo Neira Ayuso &lt;pablo@netfilter.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
[Jason: backported to 4.19 from Sasha's 5.4 backport]
Signed-off-by: Jason A. Donenfeld &lt;Jason@zx2c4.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>can: can_create_echo_skb(): fix echo skb generation: always use skb_clone()</title>
<updated>2020-11-18T18:18:42Z</updated>
<author>
<name>Oleksij Rempel</name>
<email>o.rempel@pengutronix.de</email>
</author>
<published>2019-12-18T08:39:02Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=ef02687fc78099ef3fd2eb8a150c2823fe2d9061'/>
<id>urn:sha1:ef02687fc78099ef3fd2eb8a150c2823fe2d9061</id>
<content type='text'>
[ Upstream commit 286228d382ba6320f04fa2e7c6fc8d4d92e428f4 ]

All user space generated SKBs are owned by a socket (unless injected into the
key via AF_PACKET). If a socket is closed, all associated skbs will be cleaned
up.

This leads to a problem when a CAN driver calls can_put_echo_skb() on a
unshared SKB. If the socket is closed prior to the TX complete handler,
can_get_echo_skb() and the subsequent delivering of the echo SKB to all
registered callbacks, a SKB with a refcount of 0 is delivered.

To avoid the problem, in can_get_echo_skb() the original SKB is now always
cloned, regardless of shared SKB or not. If the process exists it can now
safely discard its SKBs, without disturbing the delivery of the echo SKB.

The problem shows up in the j1939 stack, when it clones the incoming skb, which
detects the already 0 refcount.

We can easily reproduce this with following example:

testj1939 -B -r can0: &amp;
cansend can0 1823ff40#0123

WARNING: CPU: 0 PID: 293 at lib/refcount.c:25 refcount_warn_saturate+0x108/0x174
refcount_t: addition on 0; use-after-free.
Modules linked in: coda_vpu imx_vdoa videobuf2_vmalloc dw_hdmi_ahb_audio vcan
CPU: 0 PID: 293 Comm: cansend Not tainted 5.5.0-rc6-00376-g9e20dcb7040d #1
Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
Backtrace:
[&lt;c010f570&gt;] (dump_backtrace) from [&lt;c010f90c&gt;] (show_stack+0x20/0x24)
[&lt;c010f8ec&gt;] (show_stack) from [&lt;c0c3e1a4&gt;] (dump_stack+0x8c/0xa0)
[&lt;c0c3e118&gt;] (dump_stack) from [&lt;c0127fec&gt;] (__warn+0xe0/0x108)
[&lt;c0127f0c&gt;] (__warn) from [&lt;c01283c8&gt;] (warn_slowpath_fmt+0xa8/0xcc)
[&lt;c0128324&gt;] (warn_slowpath_fmt) from [&lt;c0539c0c&gt;] (refcount_warn_saturate+0x108/0x174)
[&lt;c0539b04&gt;] (refcount_warn_saturate) from [&lt;c0ad2cac&gt;] (j1939_can_recv+0x20c/0x210)
[&lt;c0ad2aa0&gt;] (j1939_can_recv) from [&lt;c0ac9dc8&gt;] (can_rcv_filter+0xb4/0x268)
[&lt;c0ac9d14&gt;] (can_rcv_filter) from [&lt;c0aca2cc&gt;] (can_receive+0xb0/0xe4)
[&lt;c0aca21c&gt;] (can_receive) from [&lt;c0aca348&gt;] (can_rcv+0x48/0x98)
[&lt;c0aca300&gt;] (can_rcv) from [&lt;c09b1fdc&gt;] (__netif_receive_skb_one_core+0x64/0x88)
[&lt;c09b1f78&gt;] (__netif_receive_skb_one_core) from [&lt;c09b2070&gt;] (__netif_receive_skb+0x38/0x94)
[&lt;c09b2038&gt;] (__netif_receive_skb) from [&lt;c09b2130&gt;] (netif_receive_skb_internal+0x64/0xf8)
[&lt;c09b20cc&gt;] (netif_receive_skb_internal) from [&lt;c09b21f8&gt;] (netif_receive_skb+0x34/0x19c)
[&lt;c09b21c4&gt;] (netif_receive_skb) from [&lt;c0791278&gt;] (can_rx_offload_napi_poll+0x58/0xb4)

Fixes: 0ae89beb283a ("can: add destructor for self generated skbs")
Signed-off-by: Oleksij Rempel &lt;o.rempel@pengutronix.de&gt;
Link: http://lore.kernel.org/r/20200124132656.22156-1-o.rempel@pengutronix.de
Acked-by: Oliver Hartkopp &lt;socketcan@hartkopp.net&gt;
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
</feed>
