linux-stable.git/kernel, branch v5.0.6

bpf: do not restore dst_reg when cur_state is freed

2019-04-03T04:27:39+00:00

commit 0803278b0b4d8eeb2b461fb698785df65a725d9e upstream.

Syzkaller hit 'KASAN: use-after-free Write in sanitize_ptr_alu' bug.

Call trace:

  dump_stack+0xbf/0x12e
  print_address_description+0x6a/0x280
  kasan_report+0x237/0x360
  sanitize_ptr_alu+0x85a/0x8d0
  adjust_ptr_min_max_vals+0x8f2/0x1ca0
  adjust_reg_min_max_vals+0x8ed/0x22e0
  do_check+0x1ca6/0x5d00
  bpf_check+0x9ca/0x2570
  bpf_prog_load+0xc91/0x1030
  __se_sys_bpf+0x61e/0x1f00
  do_syscall_64+0xc8/0x550
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fault injection trace:

  kfree+0xea/0x290
  free_func_state+0x4a/0x60
  free_verifier_state+0x61/0xe0
  push_stack+0x216/0x2f0	          <- inject failslab
  sanitize_ptr_alu+0x2b1/0x8d0
  adjust_ptr_min_max_vals+0x8f2/0x1ca0
  adjust_reg_min_max_vals+0x8ed/0x22e0
  do_check+0x1ca6/0x5d00
  bpf_check+0x9ca/0x2570
  bpf_prog_load+0xc91/0x1030
  __se_sys_bpf+0x61e/0x1f00
  do_syscall_64+0xc8/0x550
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

When kzalloc() fails in push_stack(), free_verifier_state() will free
current verifier state. As push_stack() returns, dst_reg was restored
if ptr_is_dst_reg is false. However, as member of the cur_state,
dst_reg is also freed, and error occurs when dereferencing dst_reg.
Simply fix it by testing ret of push_stack() before restoring dst_reg.

Fixes: 979d63d50c0c ("bpf: prevent out of bounds speculation on pointer arithmetic")
Signed-off-by: Xu Yu 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Greg Kroah-Hartman

cpu/hotplug: Prevent crash when CPU bringup fails on CONFIG_HOTPLUG_CPU=n

2019-04-03T04:27:38+00:00

commit 206b92353c839c0b27a0b9bec24195f93fd6cf7a upstream.

Tianyu reported a crash in a CPU hotplug teardown callback when booting a
kernel which has CONFIG_HOTPLUG_CPU disabled with the 'nosmt' boot
parameter.

It turns out that the SMP=y CONFIG_HOTPLUG_CPU=n case has been broken
forever in case that a bringup callback fails. Unfortunately this issue was
not recognized when the CPU hotplug code was reworked, so the shortcoming
just stayed in place.

When a bringup callback fails, the CPU hotplug code rolls back the
operation and takes the CPU offline.

The 'nosmt' command line argument uses a bringup failure to abort the
bringup of SMT sibling CPUs. This partial bringup is required due to the
MCE misdesign on Intel CPUs.

With CONFIG_HOTPLUG_CPU=y the rollback works perfectly fine, but
CONFIG_HOTPLUG_CPU=n lacks essential mechanisms to exercise the low level
teardown of a CPU including the synchronizations in various facilities like
RCU, NOHZ and others.

As a consequence the teardown callbacks which must be executed on the
outgoing CPU within stop machine with interrupts disabled are executed on
the control CPU in interrupt enabled and preemptible context causing the
kernel to crash and burn. The pre state machine code has a different
failure mode which is more subtle and resulting in a less obvious use after
free crash because the control side frees resources which are still in use
by the undead CPU.

But this is not a x86 only problem. Any architecture which supports the
SMP=y HOTPLUG_CPU=n combination suffers from the same issue. It's just less
likely to be triggered because in 99.99999% of the cases all bringup
callbacks succeed.

The easy solution of making HOTPLUG_CPU mandatory for SMP is not working on
all architectures as the following architectures have either no hotplug
support at all or not all subarchitectures support it:

 alpha, arc, hexagon, openrisc, riscv, sparc (32bit), mips (partial).

Crashing the kernel in such a situation is not an acceptable state
either.

Implement a minimal rollback variant by limiting the teardown to the point
where all regular teardown callbacks have been invoked and leave the CPU in
the 'dead' idle state. This has the following consequences:

 - the CPU is brought down to the point where the stop_machine takedown
   would happen.

 - the CPU stays there forever and is idle

 - The CPU is cleared in the CPU active mask, but not in the CPU online
   mask which is a legit state.

 - Interrupts are not forced away from the CPU

 - All facilities which only look at online mask would still see it, but
   that is the case during normal hotplug/unplug operations as well. It's
   just a (way) longer time frame.

This will expose issues, which haven't been exposed before or only seldom,
because now the normally transient state of being non active but online is
a permanent state. In testing this exposed already an issue vs. work queues
where the vmstat code schedules work on the almost dead CPU which ends up
in an unbound workqueue and triggers 'preemtible context' warnings. This is
not a problem of this change, it merily exposes an already existing issue.
Still this is better than crashing fully without a chance to debug it.

This is mainly thought as workaround for those architectures which do not
support HOTPLUG_CPU. All others should enforce HOTPLUG_CPU for SMP.

Fixes: 2e1a3483ce74 ("cpu/hotplug: Split out the state walk into functions")
Reported-by: Tianyu Lan 
Signed-off-by: Thomas Gleixner 
Tested-by: Tianyu Lan 
Acked-by: Greg Kroah-Hartman 
Cc: Konrad Wilk 
Cc: Josh Poimboeuf 
Cc: Mukesh Ojha 
Cc: Peter Zijlstra 
Cc: Jiri Kosina 
Cc: Rik van Riel 
Cc: Andy Lutomirski 
Cc: Micheal Kelley 
Cc: "K. Y. Srinivasan" 
Cc: Linus Torvalds 
Cc: Borislav Petkov 
Cc: K. Y. Srinivasan 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190326163811.503390616@linutronix.de
Signed-off-by: Greg Kroah-Hartman

watchdog: Respect watchdog cpumask on CPU hotplug

2019-04-03T04:27:38+00:00

commit 7dd47617114921fdd8c095509e5e7b4373cc44a1 upstream.

The rework of the watchdog core to use cpu_stop_work broke the watchdog
cpumask on CPU hotplug.

The watchdog_enable/disable() functions are now called unconditionally from
the hotplug callback, i.e. even on CPUs which are not in the watchdog
cpumask. As a consequence the watchdog can become unstoppable.

Only invoke them when the plugged CPU is in the watchdog cpumask.

Fixes: 9cf57731b63e ("watchdog/softlockup: Replace "watchdog/%u" threads with cpu_stop_work")
Reported-by: Maxime Coquelin 
Signed-off-by: Thomas Gleixner 
Tested-by: Maxime Coquelin 
Cc: Peter Zijlstra 
Cc: Oleg Nesterov 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Don Zickus 
Cc: Ricardo Neri 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1903262245490.1789@nanos.tec.linutronix.de
Signed-off-by: Greg Kroah-Hartman

tracing: initialize variable in create_dyn_event()

2019-04-03T04:27:28+00:00

commit 3dee10da2e9ff220e054a8f158cc296c797fbe81 upstream.

Fix compile warning in create_dyn_event(): 'ret' may be used uninitialized
in this function [-Wuninitialized].

Link: http://lkml.kernel.org/r/1553237900-8555-1-git-send-email-frowand.list@gmail.com

Cc: Masami Hiramatsu 
Cc: Ingo Molnar 
Cc: Tom Zanussi 
Cc: Ravi Bangoria 
Cc: stable@vger.kernel.org
Fixes: 5448d44c3855 ("tracing: Add unified dynamic event framework")
Signed-off-by: Frank Rowand 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

locking/lockdep: Add debug_locks check in __lock_downgrade()

2019-03-27T05:18:00+00:00

commit 71492580571467fb7177aade19c18ce7486267f5 upstream.

Tetsuo Handa had reported he saw an incorrect "downgrading a read lock"
warning right after a previous lockdep warning. It is likely that the
previous warning turned off lock debugging causing the lockdep to have
inconsistency states leading to the lock downgrade warning.

Fix that by add a check for debug_locks at the beginning of
__lock_downgrade().

Debugged-by: Tetsuo Handa 
Reported-by: Tetsuo Handa 
Reported-by: syzbot+53383ae265fb161ef488@syzkaller.appspotmail.com
Signed-off-by: Waiman Long 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Link: https://lkml.kernel.org/r/1547093005-26085-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

futex: Ensure that futex address is aligned in handle_futex_death()

2019-03-27T05:17:54+00:00

commit 5a07168d8d89b00fe1760120714378175b3ef992 upstream.

The futex code requires that the user space addresses of futexes are 32bit
aligned. sys_futex() checks this in futex_get_keys() but the robust list
code has no alignment check in place.

As a consequence the kernel crashes on architectures with strict alignment
requirements in handle_futex_death() when trying to cmpxchg() on an
unaligned futex address which was retrieved from the robust list.

[ tglx: Rewrote changelog, proper sizeof() based alignement check and add
  	comment ]

Fixes: 0771dfefc9e5 ("[PATCH] lightweight robust futexes: core")
Signed-off-by: Chen Jie 
Signed-off-by: Thomas Gleixner 
Cc: 
Cc: 
Cc: 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1552621478-119787-1-git-send-email-chenjie6@huawei.com
Signed-off-by: Greg Kroah-Hartman

rcu: Do RCU GP kthread self-wakeup from softirq and interrupt

2019-03-23T19:11:38+00:00

commit 1d1f898df6586c5ea9aeaf349f13089c6fa37903 upstream.

The rcu_gp_kthread_wake() function is invoked when it might be necessary
to wake the RCU grace-period kthread.  Because self-wakeups are normally
a useless waste of CPU cycles, if rcu_gp_kthread_wake() is invoked from
this kthread, it naturally refuses to do the wakeup.

Unfortunately, natural though it might be, this heuristic fails when
rcu_gp_kthread_wake() is invoked from an interrupt or softirq handler
that interrupted the grace-period kthread just after the final check of
the wait-event condition but just before the schedule() call.  In this
case, a wakeup is required, even though the call to rcu_gp_kthread_wake()
is within the RCU grace-period kthread's context.  Failing to provide
this wakeup can result in grace periods failing to start, which in turn
results in out-of-memory conditions.

This race window is quite narrow, but it actually did happen during real
testing.  It would of course need to be fixed even if it was strictly
theoretical in nature.

This patch does not Cc stable because it does not apply cleanly to
earlier kernel versions.

Fixes: 48a7639ce80c ("rcu: Make callers awaken grace-period kthread")
Reported-by: "He, Bo" 
Co-developed-by: "Zhang, Jun" 
Co-developed-by: "He, Bo" 
Co-developed-by: "xiao, jin" 
Co-developed-by: Bai, Jie A 
Signed-off: "Zhang, Jun" 
Signed-off: "He, Bo" 
Signed-off: "xiao, jin" 
Signed-off: Bai, Jie A 
Signed-off-by: "Zhang, Jun" 
[ paulmck: Switch from !in_softirq() to "!in_interrupt() &&
  !in_serving_softirq() to avoid redundant wakeups and to also handle the
  interrupt-handler scenario as well as the softirq-handler scenario that
  actually occurred in testing. ]
Signed-off-by: Paul E. McKenney 
Link: https://lkml.kernel.org/r/CD6925E8781EFD4D8E11882D20FC406D52A11F61@SHSMSX104.ccr.corp.intel.com
Signed-off-by: Greg Kroah-Hartman

swiotlb: Add is_swiotlb_active() function

2019-03-23T19:11:26+00:00

commit 492366f7b4237257ef50ca9c431a6a0d50225aca upstream.

This function will be used from dma_direct code to determine
the maximum segment size of a dma mapping.

Cc: stable@vger.kernel.org
Reviewed-by: Konrad Rzeszutek Wilk 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Joerg Roedel 
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Greg Kroah-Hartman

swiotlb: Introduce swiotlb_max_mapping_size()

2019-03-23T19:11:26+00:00

commit abe420bfae528c92bd8cc5ecb62dc95672b1fd6f upstream.

The function returns the maximum size that can be remapped
by the SWIOTLB implementation. This function will be later
exposed to users through the DMA-API.

Cc: stable@vger.kernel.org
Reviewed-by: Konrad Rzeszutek Wilk 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Joerg Roedel 
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Greg Kroah-Hartman

dma: Introduce dma_max_mapping_size()

2019-03-23T19:11:26+00:00

commit 133d624b1cee16906134e92d5befb843b58bcf31 upstream.

The function returns the maximum size that can be mapped
using DMA-API functions. The patch also adds the
implementation for direct DMA and a new dma_map_ops pointer
so that other implementations can expose their limit.

Cc: stable@vger.kernel.org
Reviewed-by: Konrad Rzeszutek Wilk 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Joerg Roedel 
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Greg Kroah-Hartman