linux-stable.git/kernel, branch v5.6.7

bpf: fix buggy r0 retval refinement for tracing helpers

2020-04-23T08:38:26+00:00

[ no upstream commit ]

See the glory details in 100605035e15 ("bpf: Verifier, do_refine_retval_range
may clamp umin to 0 incorrectly") for why 849fa50662fb ("bpf/verifier: refine
retval R0 state for bpf_get_stack helper") is buggy. The whole series however
is not suitable for stable since it adds significant amount [0] of verifier
complexity in order to add 32bit subreg tracking. Something simpler is needed.

Unfortunately, reverting 849fa50662fb ("bpf/verifier: refine retval R0 state
for bpf_get_stack helper") or just cherry-picking 100605035e15 ("bpf: Verifier,
do_refine_retval_range may clamp umin to 0 incorrectly") is not an option since
it will break existing tracing programs badly (at least those that are using
bpf_get_stack() and bpf_probe_read_str() helpers). Not fixing it in stable is
also not an option since on 4.19 kernels an error will cause a soft-lockup due
to hitting dead-code sanitized branch since we don't hard-wire such branches
in old kernels yet. But even then for 5.x 849fa50662fb ("bpf/verifier: refine
retval R0 state for bpf_get_stack helper") would cause wrong bounds on the
verifier simluation when an error is hit.

In one of the earlier iterations of mentioned patch series for upstream there
was the concern that just using smax_value in do_refine_retval_range() would
nuke bounds by subsequent <<32 >>32 shifts before the comparison against 0 [1]
which eventually led to the 32bit subreg tracking in the first place. While I
initially went for implementing the idea [1] to pattern match the two shift
operations, it turned out to be more complex than actually needed, meaning, we
could simply treat do_refine_retval_range() similarly to how we branch off
verification for conditionals or under speculation, that is, pushing a new
reg state to the stack for later verification. This means, instead of verifying
the current path with the ret_reg in [S32MIN, msize_max_value] interval where
later bounds would get nuked, we split this into two: i) for the success case
where ret_reg can be in [0, msize_max_value], and ii) for the error case with
ret_reg known to be in interval [S32MIN, -1]. Latter will preserve the bounds
during these shift patterns and can match reg < 0 test. test_progs also succeed
with this approach.

  [0] https://lore.kernel.org/bpf/158507130343.15666.8018068546764556975.stgit@john-Precision-5820-Tower/
  [1] https://lore.kernel.org/bpf/158015334199.28573.4940395881683556537.stgit@john-XPS-13-9370/T/#m2e0ad1d5949131014748b6daa48a3495e7f0456d

Fixes: 849fa50662fb ("bpf/verifier: refine retval R0 state for bpf_get_stack helper")
Reported-by: Lorenzo Fontana 
Reported-by: Leonardo Di Donato 
Reported-by: John Fastabend 
Signed-off-by: Daniel Borkmann 
Acked-by: Alexei Starovoitov 
Acked-by: John Fastabend 
Tested-by: John Fastabend 
Signed-off-by: Greg Kroah-Hartman

locktorture: Print ratio of acquisitions, not failures

2020-04-23T08:38:24+00:00

commit 80c503e0e68fbe271680ab48f0fe29bc034b01b7 upstream.

The __torture_print_stats() function in locktorture.c carefully
initializes local variable "min" to statp[0].n_lock_acquired, but
then compares it to statp[i].n_lock_fail.  Given that the .n_lock_fail
field should normally be zero, and given the initialization, it seems
reasonable to display the maximum and minimum number acquisitions
instead of miscomputing the maximum and minimum number of failures.
This commit therefore switches from failures to acquisitions.

And this turns out to be not only a day-zero bug, but entirely my
own fault.  I hate it when that happens!

Fixes: 0af3fe1efa53 ("locktorture: Add a lock-torture kernel module")
Reported-by: Will Deacon 
Signed-off-by: Paul E. McKenney 
Acked-by: Will Deacon 
Cc: Davidlohr Bueso 
Cc: Josh Triplett 
Cc: Peter Zijlstra 
Signed-off-by: Greg Kroah-Hartman

dma-debug: fix displaying of dma allocation type

2020-04-23T08:38:22+00:00

commit 9bb50ed7470944238ec8e30a94ef096caf9056ee upstream.

The commit 2e05ea5cdc1a ("dma-mapping: implement dma_map_single_attrs using
dma_map_page_attrs") removed "dma_debug_page" enum, but missed to update
type2name string table. This causes incorrect displaying of dma allocation
type.
Fix it by removing "page" string from type2name string table and switch to
use named initializers.

Before (dma_alloc_coherent()):
k3-ringacc 4b800000.ringacc: scather-gather idx 2208 P=d1140000 N=d114 D=d1140000 L=40 DMA_BIDIRECTIONAL dma map error check not applicable
k3-ringacc 4b800000.ringacc: scather-gather idx 2216 P=d1150000 N=d115 D=d1150000 L=40 DMA_BIDIRECTIONAL dma map error check not applicable

After:
k3-ringacc 4b800000.ringacc: coherent idx 2208 P=d1140000 N=d114 D=d1140000 L=40 DMA_BIDIRECTIONAL dma map error check not applicable
k3-ringacc 4b800000.ringacc: coherent idx 2216 P=d1150000 N=d115 D=d1150000 L=40 DMA_BIDIRECTIONAL dma map error check not applicable

Fixes: 2e05ea5cdc1a ("dma-mapping: implement dma_map_single_attrs using dma_map_page_attrs")
Signed-off-by: Grygorii Strashko 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Greg Kroah-Hartman

dma-coherent: fix integer overflow in the reserved-memory dma allocation

2020-04-23T08:38:05+00:00

[ Upstream commit 286c21de32b904131f8cf6a36ce40b8b0c9c5da3 ]

pageno is an int and the PAGE_SHIFT shift is done on an int,
overflowing if the memory is bigger than 2G

This can be reproduced using for example a reserved-memory of 4G

reserved-memory {
		    #address-cells = <2>;
		    #size-cells = <2>;
		    ranges;

		    reserved_dma: buffer@0 {
		        compatible = "shared-dma-pool";
		        no-map;
		        reg = <0x5 0x00000000 0x1 0x0>;
        };
};

Signed-off-by: Kevin Grandemange 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Sasha Levin

bpf: Prevent re-mmap()'ing BPF map as writable for initially r/o mapping

2020-04-23T08:37:51+00:00

commit 1f6cb19be2e231fe092f40decb71f066eba090d7 upstream.

VM_MAYWRITE flag during initial memory mapping determines if already mmap()'ed
pages can be later remapped as writable ones through mprotect() call. To
prevent user application to rewrite contents of memory-mapped as read-only and
subsequently frozen BPF map, remove VM_MAYWRITE flag completely on initially
read-only mapping.

Alternatively, we could treat any memory-mapping on unfrozen map as writable
and bump writecnt instead. But there is little legitimate reason to map
BPF map as read-only and then re-mmap() it as writable through mprotect(),
instead of just mmap()'ing it as read/write from the very beginning.

Also, at the suggestion of Jann Horn, drop unnecessary refcounting in mmap
operations. We can just rely on VMA holding reference to BPF map's file
properly.

Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY")
Reported-by: Jann Horn 
Signed-off-by: Andrii Nakryiko 
Signed-off-by: Daniel Borkmann 
Reviewed-by: Jann Horn 
Link: https://lore.kernel.org/bpf/20200410202613.3679837-1-andriin@fb.com
Signed-off-by: Greg Kroah-Hartman

proc, time/namespace: Show clock symbolic names in /proc/pid/timens_offsets

2020-04-21T07:08:15+00:00

commit 94d440d618467806009c8edc70b094d64e12ee5a upstream.

Michael Kerrisk suggested to replace numeric clock IDs with symbolic names.

Now the content of these files looks like this:
$ cat /proc/774/timens_offsets
monotonic      864000         0
boottime      1728000         0

For setting offsets, both representations of clocks (numeric and symbolic)
can be used.

As for compatibility, it is acceptable to change things as long as
userspace doesn't care. The format of timens_offsets files is very new and
there are no userspace tools yet which rely on this format.

But three projects crun, util-linux and criu rely on the interface of
setting time offsets and this is why it's required to continue supporting
the numeric clock IDs on write.

Fixes: 04a8682a71be ("fs/proc: Introduce /proc/pid/timens_offsets")
Suggested-by: Michael Kerrisk 
Signed-off-by: Andrei Vagin 
Signed-off-by: Thomas Gleixner 
Tested-by: Michael Kerrisk 
Acked-by: Michael Kerrisk 
Cc: Andrew Morton 
Cc: Eric W. Biederman 
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20200411154031.642557-1-avagin@gmail.com
Signed-off-by: Greg Kroah-Hartman

rcu: Don't acquire lock in NMI handler in rcu_nmi_enter_common()

2020-04-21T07:08:14+00:00

commit bf37da98c51825c90432d340e135cced37a7460d upstream.

The rcu_nmi_enter_common() function can be invoked both in interrupt
and NMI handlers.  If it is invoked from process context (as opposed
to userspace or idle context) on a nohz_full CPU, it might acquire the
CPU's leaf rcu_node structure's ->lock.  Because this lock is held only
with interrupts disabled, this is safe from an interrupt handler, but
doing so from an NMI handler can result in self-deadlock.

This commit therefore adds "irq" to the "if" condition so as to only
acquire the ->lock from irq handlers or process context, never from
an NMI handler.

Fixes: 5b14557b073c ("rcu: Avoid tick_dep_set_cpu() misordering")
Reported-by: Thomas Gleixner 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Joel Fernandes (Google) 
Cc:  # 5.5.x
Signed-off-by: Greg Kroah-Hartman

tracing: Fix the race between registering 'snapshot' event trigger and triggering 'snapshot' operation

2020-04-21T07:08:09+00:00

commit 0bbe7f719985efd9adb3454679ecef0984cb6800 upstream.

Traced event can trigger 'snapshot' operation(i.e. calls snapshot_trigger()
or snapshot_count_trigger()) when register_snapshot_trigger() has completed
registration but doesn't allocate buffer for 'snapshot' event trigger.  In
the rare case, 'snapshot' operation always detects the lack of allocated
buffer so make register_snapshot_trigger() allocate buffer first.

trigger-snapshot.tc in kselftest reproduces the issue on slow vm:
-----------------------------------------------------------
cat trace
...
ftracetest-3028  [002] ....   236.784290: sched_process_fork: comm=ftracetest pid=3028 child_comm=ftracetest child_pid=3036
     <...>-2875  [003] ....   240.460335: tracing_snapshot_instance_cond: *** SNAPSHOT NOT ALLOCATED ***
     <...>-2875  [003] ....   240.460338: tracing_snapshot_instance_cond: *** stopping trace here!   ***
-----------------------------------------------------------

Link: http://lkml.kernel.org/r/20200414015145.66236-1-yangx.jy@cn.fujitsu.com

Cc: stable@vger.kernel.org
Fixes: 93e31ffbf417a ("tracing: Add 'snapshot' event trigger command")
Signed-off-by: Xiao Yang 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

bpf: Fix tnum constraints for 32-bit comparisons

2020-04-17T14:13:48+00:00

[ Upstream commit 604dca5e3af1db98bd123b7bfc02b017af99e3a0 ]

The BPF verifier tried to track values based on 32-bit comparisons by
(ab)using the tnum state via 581738a681b6 ("bpf: Provide better register
bounds after jmp32 instructions"). The idea is that after a check like
this:

    if ((u32)r0 > 3)
      exit

We can't meaningfully constrain the arithmetic-range-based tracking, but
we can update the tnum state to (value=0,mask=0xffff'ffff'0000'0003).
However, the implementation from 581738a681b6 didn't compute the tnum
constraint based on the fixed operand, but instead derives it from the
arithmetic-range-based tracking. This means that after the following
sequence of operations:

    if (r0 >= 0x1'0000'0001)
      exit
    if ((u32)r0 > 7)
      exit

The verifier assumed that the lower half of r0 is in the range (0, 0)
and apply the tnum constraint (value=0,mask=0xffff'ffff'0000'0000) thus
causing the overall tnum to be (value=0,mask=0x1'0000'0000), which was
incorrect. Provide a fixed implementation.

Fixes: 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions")
Signed-off-by: Jann Horn 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20200330160324.15259-3-daniel@iogearbox.net
Signed-off-by: Sasha Levin

perf/core: Remove 'struct sched_in_data'

2020-04-17T14:13:48+00:00

[ Upstream commit 2c2366c7548ecee65adfd264517ddf50f9e2d029 ]

We can deduce the ctx and cpuctx from the event, no need to pass them
along. Remove the structure and pass in can_add_hw directly.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin