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<title>user/sven/linux.git/include, branch v4.20.12</title>
<subtitle>Linux Kernel
</subtitle>
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<updated>2019-02-23T08:08:07Z</updated>
<entry>
<title>ax25: fix possible use-after-free</title>
<updated>2019-02-23T08:08:07Z</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2019-01-22T18:40:59Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=578636114de457240a817063ebb6b4b07527a680'/>
<id>urn:sha1:578636114de457240a817063ebb6b4b07527a680</id>
<content type='text'>
commit 63530aba7826a0f8e129874df9c4d264f9db3f9e upstream.

syzbot found that ax25 routes where not properly protected
against concurrent use [1].

In this particular report the bug happened while
copying ax25-&gt;digipeat.

Fix this problem by making sure we call ax25_get_route()
while ax25_route_lock is held, so that no modification
could happen while using the route.

The current two ax25_get_route() callers do not sleep,
so this change should be fine.

Once we do that, ax25_get_route() no longer needs to
grab a reference on the found route.

[1]
ax25_connect(): syz-executor0 uses autobind, please contact jreuter@yaina.de
BUG: KASAN: use-after-free in memcpy include/linux/string.h:352 [inline]
BUG: KASAN: use-after-free in kmemdup+0x42/0x60 mm/util.c:113
Read of size 66 at addr ffff888066641a80 by task syz-executor2/531

ax25_connect(): syz-executor0 uses autobind, please contact jreuter@yaina.de
CPU: 1 PID: 531 Comm: syz-executor2 Not tainted 5.0.0-rc2+ #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1db/0x2d0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x123/0x190 mm/kasan/generic.c:191
 memcpy+0x24/0x50 mm/kasan/common.c:130
 memcpy include/linux/string.h:352 [inline]
 kmemdup+0x42/0x60 mm/util.c:113
 kmemdup include/linux/string.h:425 [inline]
 ax25_rt_autobind+0x25d/0x750 net/ax25/ax25_route.c:424
 ax25_connect.cold+0x30/0xa4 net/ax25/af_ax25.c:1224
 __sys_connect+0x357/0x490 net/socket.c:1664
 __do_sys_connect net/socket.c:1675 [inline]
 __se_sys_connect net/socket.c:1672 [inline]
 __x64_sys_connect+0x73/0xb0 net/socket.c:1672
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458099
Code: 6d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 &lt;48&gt; 3d 01 f0 ff ff 0f 83 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f870ee22c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458099
RDX: 0000000000000048 RSI: 0000000020000080 RDI: 0000000000000005
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
ax25_connect(): syz-executor4 uses autobind, please contact jreuter@yaina.de
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f870ee236d4
R13: 00000000004be48e R14: 00000000004ce9a8 R15: 00000000ffffffff

Allocated by task 526:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_kmalloc mm/kasan/common.c:496 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:469
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:504
ax25_connect(): syz-executor5 uses autobind, please contact jreuter@yaina.de
 kmem_cache_alloc_trace+0x151/0x760 mm/slab.c:3609
 kmalloc include/linux/slab.h:545 [inline]
 ax25_rt_add net/ax25/ax25_route.c:95 [inline]
 ax25_rt_ioctl+0x3b9/0x1270 net/ax25/ax25_route.c:233
 ax25_ioctl+0x322/0x10b0 net/ax25/af_ax25.c:1763
 sock_do_ioctl+0xe2/0x400 net/socket.c:950
 sock_ioctl+0x32f/0x6c0 net/socket.c:1074
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0x107b/0x17d0 fs/ioctl.c:696
 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

ax25_connect(): syz-executor5 uses autobind, please contact jreuter@yaina.de
Freed by task 550:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:458
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:466
 __cache_free mm/slab.c:3487 [inline]
 kfree+0xcf/0x230 mm/slab.c:3806
 ax25_rt_add net/ax25/ax25_route.c:92 [inline]
 ax25_rt_ioctl+0x304/0x1270 net/ax25/ax25_route.c:233
 ax25_ioctl+0x322/0x10b0 net/ax25/af_ax25.c:1763
 sock_do_ioctl+0xe2/0x400 net/socket.c:950
 sock_ioctl+0x32f/0x6c0 net/socket.c:1074
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0x107b/0x17d0 fs/ioctl.c:696
 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888066641a80
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 0 bytes inside of
 96-byte region [ffff888066641a80, ffff888066641ae0)
The buggy address belongs to the page:
page:ffffea0001999040 count:1 mapcount:0 mapping:ffff88812c3f04c0 index:0x0
flags: 0x1fffc0000000200(slab)
ax25_connect(): syz-executor4 uses autobind, please contact jreuter@yaina.de
raw: 01fffc0000000200 ffffea0001817948 ffffea0002341dc8 ffff88812c3f04c0
raw: 0000000000000000 ffff888066641000 0000000100000020 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888066641980: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888066641a00: 00 00 00 00 00 00 00 00 02 fc fc fc fc fc fc fc
&gt;ffff888066641a80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                   ^
 ffff888066641b00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888066641b80: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Reported-by: syzbot &lt;syzkaller@googlegroups.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>efi/arm: Revert "Defer persistent reservations until after paging_init()"</title>
<updated>2019-02-23T08:08:06Z</updated>
<author>
<name>Ard Biesheuvel</name>
<email>ard.biesheuvel@linaro.org</email>
</author>
<published>2019-02-19T19:03:13Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=da9365ad7b2c3dc9366ddc2789ff86d1c25648a4'/>
<id>urn:sha1:da9365ad7b2c3dc9366ddc2789ff86d1c25648a4</id>
<content type='text'>
Commit 582a32e708823e5957fd73ccd78dc4a9e49d21ea upstream.

This reverts commit eff896288872d687d9662000ec9ae11b6d61766f, which
deferred the processing of persistent memory reservations to a point
where the memory may have already been allocated and overwritten,
defeating the purpose.

Signed-off-by: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Acked-by: Will Deacon &lt;will.deacon@arm.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Marc Zyngier &lt;marc.zyngier@arm.com&gt;
Cc: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20190215123333.21209-3-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Signed-off-by: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>arm64, mm, efi: Account for GICv3 LPI tables in static memblock reserve table</title>
<updated>2019-02-23T08:08:06Z</updated>
<author>
<name>Ard Biesheuvel</name>
<email>ard.biesheuvel@linaro.org</email>
</author>
<published>2019-02-19T19:03:12Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=de3d833d6bdd8ba56252556038eccf2118e67c05'/>
<id>urn:sha1:de3d833d6bdd8ba56252556038eccf2118e67c05</id>
<content type='text'>
Commit 8a5b403d71affa098009cc3dff1b2c45113021ad upstream.

In the irqchip and EFI code, we have what basically amounts to a quirk
to work around a peculiarity in the GICv3 architecture, which permits
the system memory address of LPI tables to be programmable only once
after a CPU reset. This means kexec kernels must use the same memory
as the first kernel, and thus ensure that this memory has not been
given out for other purposes by the time the ITS init code runs, which
is not very early for secondary CPUs.

On systems with many CPUs, these reservations could overflow the
memblock reservation table, and this was addressed in commit:

  eff896288872 ("efi/arm: Defer persistent reservations until after paging_init()")

However, this turns out to have made things worse, since the allocation
of page tables and heap space for the resized memblock reservation table
itself may overwrite the regions we are attempting to reserve, which may
cause all kinds of corruption, also considering that the ITS will still
be poking bits into that memory in response to incoming MSIs.

So instead, let's grow the static memblock reservation table on such
systems so it can accommodate these reservations at an earlier time.
This will permit us to revert the above commit in a subsequent patch.

[ mingo: Minor cleanups. ]

Signed-off-by: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Acked-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Acked-by: Will Deacon &lt;will.deacon@arm.com&gt;
Acked-by: Marc Zyngier &lt;marc.zyngier@arm.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20190215123333.21209-2-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
[ ardb: Double the size of the slack to account for the lack of an
        optimization that was introduced in mainline after the release
        of v4.20. ]
Signed-off-by: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>net: Add header for usage of fls64()</title>
<updated>2019-02-23T08:08:06Z</updated>
<author>
<name>David S. Miller</name>
<email>davem@davemloft.net</email>
</author>
<published>2019-02-16T21:44:39Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=0009ef5717b2af2a69e5e60ec7884b341855323f'/>
<id>urn:sha1:0009ef5717b2af2a69e5e60ec7884b341855323f</id>
<content type='text'>
[ Upstream commit 8681ef1f3d295bd3600315325f3b3396d76d02f6 ]

Fixes: 3b89ea9c5902 ("net: Fix for_each_netdev_feature on Big endian")
Suggested-by: Eric Dumazet &lt;eric.dumazet@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>net: Fix for_each_netdev_feature on Big endian</title>
<updated>2019-02-23T08:08:05Z</updated>
<author>
<name>Hauke Mehrtens</name>
<email>hauke.mehrtens@intel.com</email>
</author>
<published>2019-02-15T16:58:54Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=6d7a9a07e0f7c46d5cae44f6a635bc2930066a1b'/>
<id>urn:sha1:6d7a9a07e0f7c46d5cae44f6a635bc2930066a1b</id>
<content type='text'>
[ Upstream commit 3b89ea9c5902acccdbbdec307c85edd1bf52515e ]

The features attribute is of type u64 and stored in the native endianes on
the system. The for_each_set_bit() macro takes a pointer to a 32 bit array
and goes over the bits in this area. On little Endian systems this also
works with an u64 as the most significant bit is on the highest address,
but on big endian the words are swapped. When we expect bit 15 here we get
bit 47 (15 + 32).

This patch converts it more or less to its own for_each_set_bit()
implementation which works on 64 bit integers directly. This is then
completely in host endianness and should work like expected.

Fixes: fd867d51f ("net/core: generic support for disabling netdev features down stack")
Signed-off-by: Hauke Mehrtens &lt;hauke.mehrtens@intel.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>net: ipv4: use a dedicated counter for icmp_v4 redirect packets</title>
<updated>2019-02-23T08:08:05Z</updated>
<author>
<name>Lorenzo Bianconi</name>
<email>lorenzo.bianconi@redhat.com</email>
</author>
<published>2019-02-06T18:18:04Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=5d5c002b1b24c3d037abb19f008ca343f176f219'/>
<id>urn:sha1:5d5c002b1b24c3d037abb19f008ca343f176f219</id>
<content type='text'>
[ Upstream commit c09551c6ff7fe16a79a42133bcecba5fc2fc3291 ]

According to the algorithm described in the comment block at the
beginning of ip_rt_send_redirect, the host should try to send
'ip_rt_redirect_number' ICMP redirect packets with an exponential
backoff and then stop sending them at all assuming that the destination
ignores redirects.
If the device has previously sent some ICMP error packets that are
rate-limited (e.g TTL expired) and continues to receive traffic,
the redirect packets will never be transmitted. This happens since
peer-&gt;rate_tokens will be typically greater than 'ip_rt_redirect_number'
and so it will never be reset even if the redirect silence timeout
(ip_rt_redirect_silence) has elapsed without receiving any packet
requiring redirects.

Fix it by using a dedicated counter for the number of ICMP redirect
packets that has been sent by the host

I have not been able to identify a given commit that introduced the
issue since ip_rt_send_redirect implements the same rate-limiting
algorithm from commit 1da177e4c3f4 ("Linux-2.6.12-rc2")

Signed-off-by: Lorenzo Bianconi &lt;lorenzo.bianconi@redhat.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>mmc: block: handle complete_work on separate workqueue</title>
<updated>2019-02-20T09:29:11Z</updated>
<author>
<name>Zachary Hays</name>
<email>zhays@lexmark.com</email>
</author>
<published>2019-02-07T15:03:08Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=1fdf7b8b061251324af0e53046605c478024f95f'/>
<id>urn:sha1:1fdf7b8b061251324af0e53046605c478024f95f</id>
<content type='text'>
commit dcf6e2e38a1c7ccbc535de5e1d9b14998847499d upstream.

The kblockd workqueue is created with the WQ_MEM_RECLAIM flag set.
This generates a rescuer thread for that queue that will trigger when
the CPU is under heavy load and collect the uncompleted work.

In the case of mmc, this creates the possibility of a deadlock when
there are multiple partitions on the device as other blk-mq work is
also run on the same queue. For example:

- worker 0 claims the mmc host to work on partition 1
- worker 1 attempts to claim the host for partition 2 but has to wait
  for worker 0 to finish
- worker 0 schedules complete_work to release the host
- rescuer thread is triggered after time-out and collects the dangling
  work
- rescuer thread attempts to complete the work in order starting with
  claim host
- the task to release host is now blocked by a task to claim it and
  will never be called

The above results in multiple hung tasks that lead to failures to
mount partitions.

Handling complete_work on a separate workqueue avoids this by keeping
the work completion tasks separate from the other blk-mq work. This
allows the host to be released without getting blocked by other tasks
attempting to claim the host.

Signed-off-by: Zachary Hays &lt;zhays@lexmark.com&gt;
Fixes: 81196976ed94 ("mmc: block: Add blk-mq support")
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Ulf Hansson &lt;ulf.hansson@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>perf/x86: Add check_period PMU callback</title>
<updated>2019-02-20T09:29:10Z</updated>
<author>
<name>Jiri Olsa</name>
<email>jolsa@redhat.com</email>
</author>
<published>2019-02-04T12:35:32Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=6a66c2d00018fad3b79b75980c0f3602c5d188fc'/>
<id>urn:sha1:6a66c2d00018fad3b79b75980c0f3602c5d188fc</id>
<content type='text'>
commit 81ec3f3c4c4d78f2d3b6689c9816bfbdf7417dbb upstream.

Vince (and later on Ravi) reported crashes in the BTS code during
fuzzing with the following backtrace:

  general protection fault: 0000 [#1] SMP PTI
  ...
  RIP: 0010:perf_prepare_sample+0x8f/0x510
  ...
  Call Trace:
   &lt;IRQ&gt;
   ? intel_pmu_drain_bts_buffer+0x194/0x230
   intel_pmu_drain_bts_buffer+0x160/0x230
   ? tick_nohz_irq_exit+0x31/0x40
   ? smp_call_function_single_interrupt+0x48/0xe0
   ? call_function_single_interrupt+0xf/0x20
   ? call_function_single_interrupt+0xa/0x20
   ? x86_schedule_events+0x1a0/0x2f0
   ? x86_pmu_commit_txn+0xb4/0x100
   ? find_busiest_group+0x47/0x5d0
   ? perf_event_set_state.part.42+0x12/0x50
   ? perf_mux_hrtimer_restart+0x40/0xb0
   intel_pmu_disable_event+0xae/0x100
   ? intel_pmu_disable_event+0xae/0x100
   x86_pmu_stop+0x7a/0xb0
   x86_pmu_del+0x57/0x120
   event_sched_out.isra.101+0x83/0x180
   group_sched_out.part.103+0x57/0xe0
   ctx_sched_out+0x188/0x240
   ctx_resched+0xa8/0xd0
   __perf_event_enable+0x193/0x1e0
   event_function+0x8e/0xc0
   remote_function+0x41/0x50
   flush_smp_call_function_queue+0x68/0x100
   generic_smp_call_function_single_interrupt+0x13/0x30
   smp_call_function_single_interrupt+0x3e/0xe0
   call_function_single_interrupt+0xf/0x20
   &lt;/IRQ&gt;

The reason is that while event init code does several checks
for BTS events and prevents several unwanted config bits for
BTS event (like precise_ip), the PERF_EVENT_IOC_PERIOD allows
to create BTS event without those checks being done.

Following sequence will cause the crash:

If we create an 'almost' BTS event with precise_ip and callchains,
and it into a BTS event it will crash the perf_prepare_sample()
function because precise_ip events are expected to come
in with callchain data initialized, but that's not the
case for intel_pmu_drain_bts_buffer() caller.

Adding a check_period callback to be called before the period
is changed via PERF_EVENT_IOC_PERIOD. It will deny the change
if the event would become BTS. Plus adding also the limit_period
check as well.

Reported-by: Vince Weaver &lt;vincent.weaver@maine.edu&gt;
Signed-off-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Acked-by: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@kernel.org&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Naveen N. Rao &lt;naveen.n.rao@linux.vnet.ibm.com&gt;
Cc: Ravi Bangoria &lt;ravi.bangoria@linux.ibm.com&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: http://lkml.kernel.org/r/20190204123532.GA4794@krava
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVM</title>
<updated>2019-02-12T19:02:37Z</updated>
<author>
<name>Josh Poimboeuf</name>
<email>jpoimboe@redhat.com</email>
</author>
<published>2019-01-30T13:13:58Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=f29a8be0e5d28f89c835cbae700e67a383280916'/>
<id>urn:sha1:f29a8be0e5d28f89c835cbae700e67a383280916</id>
<content type='text'>
commit b284909abad48b07d3071a9fc9b5692b3e64914b upstream.

With the following commit:

  73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS")

... the hotplug code attempted to detect when SMT was disabled by BIOS,
in which case it reported SMT as permanently disabled.  However, that
code broke a virt hotplug scenario, where the guest is booted with only
primary CPU threads, and a sibling is brought online later.

The problem is that there doesn't seem to be a way to reliably
distinguish between the HW "SMT disabled by BIOS" case and the virt
"sibling not yet brought online" case.  So the above-mentioned commit
was a bit misguided, as it permanently disabled SMT for both cases,
preventing future virt sibling hotplugs.

Going back and reviewing the original problems which were attempted to
be solved by that commit, when SMT was disabled in BIOS:

  1) /sys/devices/system/cpu/smt/control showed "on" instead of
     "notsupported"; and

  2) vmx_vm_init() was incorrectly showing the L1TF_MSG_SMT warning.

I'd propose that we instead consider #1 above to not actually be a
problem.  Because, at least in the virt case, it's possible that SMT
wasn't disabled by BIOS and a sibling thread could be brought online
later.  So it makes sense to just always default the smt control to "on"
to allow for that possibility (assuming cpuid indicates that the CPU
supports SMT).

The real problem is #2, which has a simple fix: change vmx_vm_init() to
query the actual current SMT state -- i.e., whether any siblings are
currently online -- instead of looking at the SMT "control" sysfs value.

So fix it by:

  a) reverting the original "fix" and its followup fix:

     73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS")
     bc2d8d262cba ("cpu/hotplug: Fix SMT supported evaluation")

     and

  b) changing vmx_vm_init() to query the actual current SMT state --
     instead of the sysfs control value -- to determine whether the L1TF
     warning is needed.  This also requires the 'sched_smt_present'
     variable to exported, instead of 'cpu_smt_control'.

Fixes: 73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS")
Reported-by: Igor Mammedov &lt;imammedo@redhat.com&gt;
Signed-off-by: Josh Poimboeuf &lt;jpoimboe@redhat.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Joe Mario &lt;jmario@redhat.com&gt;
Cc: Jiri Kosina &lt;jikos@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: kvm@vger.kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/e3a85d585da28cc333ecbc1e78ee9216e6da9396.1548794349.git.jpoimboe@redhat.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;


</content>
</entry>
<entry>
<title>HID: debug: fix the ring buffer implementation</title>
<updated>2019-02-12T19:02:36Z</updated>
<author>
<name>Vladis Dronov</name>
<email>vdronov@redhat.com</email>
</author>
<published>2019-01-29T10:58:35Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=a8d5fb2f83c533379b8e78f5647c412e47009a46'/>
<id>urn:sha1:a8d5fb2f83c533379b8e78f5647c412e47009a46</id>
<content type='text'>
commit 13054abbaa4f1fd4e6f3b4b63439ec033b4c8035 upstream.

Ring buffer implementation in hid_debug_event() and hid_debug_events_read()
is strange allowing lost or corrupted data. After commit 717adfdaf147
("HID: debug: check length before copy_to_user()") it is possible to enter
an infinite loop in hid_debug_events_read() by providing 0 as count, this
locks up a system. Fix this by rewriting the ring buffer implementation
with kfifo and simplify the code.

This fixes CVE-2019-3819.

v2: fix an execution logic and add a comment
v3: use __set_current_state() instead of set_current_state()

Link: https://bugzilla.redhat.com/show_bug.cgi?id=1669187
Cc: stable@vger.kernel.org # v4.18+
Fixes: cd667ce24796 ("HID: use debugfs for events/reports dumping")
Fixes: 717adfdaf147 ("HID: debug: check length before copy_to_user()")
Signed-off-by: Vladis Dronov &lt;vdronov@redhat.com&gt;
Reviewed-by: Oleg Nesterov &lt;oleg@redhat.com&gt;
Signed-off-by: Benjamin Tissoires &lt;benjamin.tissoires@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
</feed>
