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  1. 12 Jun, 2018 2 commits
    • Kees Cook's avatar
      treewide: kmalloc() -> kmalloc_array() · 6da2ec56
      Kees Cook authored 
      
The kmalloc() function has a 2-factor argument form, kmalloc_array(). This
patch replaces cases of:

        kmalloc(a * b, gfp)

with:
        kmalloc_array(a * b, gfp)

as well as handling cases of:

        kmalloc(a * b * c, gfp)

with:

        kmalloc(array3_size(a, b, c), gfp)

as it's slightly less ugly than:

        kmalloc_array(array_size(a, b), c, gfp)

This does, however, attempt to ignore constant size factors like:

        kmalloc(4 * 1024, gfp)

though any constants defined via macros get caught up in the conversion.

Any factors with a sizeof() of "unsigned char", "char", and "u8" were
dropped, since they're redundant.

The tools/ directory was manually excluded, since it has its own
implementation of kmalloc().

The Coccinelle script used for this was:

// Fix redundant parens around sizeof().
@@
type TYPE;
expression THING, E;
@@

(
  kmalloc(
-	(sizeof(TYPE)) * E
+	sizeof(TYPE) * E
  , ...)
|
  kmalloc(
-	(sizeof(THING)) * E
+	sizeof(THING) * E
  , ...)
)

// Drop single-byte sizes and redundant parens.
@@
expression COUNT;
typedef u8;
typedef __u8;
@@

(
  kmalloc(
-	sizeof(u8) * (COUNT)
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(__u8) * (COUNT)
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(char) * (COUNT)
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(unsigned char) * (COUNT)
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(u8) * COUNT
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(__u8) * COUNT
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(char) * COUNT
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(unsigned char) * COUNT
+	COUNT
  , ...)
)

// 2-factor product with sizeof(type/expression) and identifier or constant.
@@
type TYPE;
expression THING;
identifier COUNT_ID;
constant COUNT_CONST;
@@

(
- kmalloc
+ kmalloc_array
  (
-	sizeof(TYPE) * (COUNT_ID)
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(TYPE) * COUNT_ID
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(TYPE) * (COUNT_CONST)
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(TYPE) * COUNT_CONST
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(THING) * (COUNT_ID)
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(THING) * COUNT_ID
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(THING) * (COUNT_CONST)
+	COUNT_CONST, sizeof(THING)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(THING) * COUNT_CONST
+	COUNT_CONST, sizeof(THING)
  , ...)
)

// 2-factor product, only identifiers.
@@
identifier SIZE, COUNT;
@@

- kmalloc
+ kmalloc_array
  (
-	SIZE * COUNT
+	COUNT, SIZE
  , ...)

// 3-factor product with 1 sizeof(type) or sizeof(expression), with
// redundant parens removed.
@@
expression THING;
identifier STRIDE, COUNT;
type TYPE;
@@

(
  kmalloc(
-	sizeof(TYPE) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kmalloc(
-	sizeof(TYPE) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kmalloc(
-	sizeof(TYPE) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kmalloc(
-	sizeof(TYPE) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kmalloc(
-	sizeof(THING) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kmalloc(
-	sizeof(THING) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kmalloc(
-	sizeof(THING) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kmalloc(
-	sizeof(THING) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
)

// 3-factor product with 2 sizeof(variable), with redundant parens removed.
@@
expression THING1, THING2;
identifier COUNT;
type TYPE1, TYPE2;
@@

(
  kmalloc(
-	sizeof(TYPE1) * sizeof(TYPE2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kmalloc(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kmalloc(
-	sizeof(THING1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kmalloc(
-	sizeof(THING1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kmalloc(
-	sizeof(TYPE1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
|
  kmalloc(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
)

// 3-factor product, only identifiers, with redundant parens removed.
@@
identifier STRIDE, SIZE, COUNT;
@@

(
  kmalloc(
-	(COUNT) * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	COUNT * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	COUNT * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	(COUNT) * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	COUNT * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	(COUNT) * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	(COUNT) * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	COUNT * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
)

// Any remaining multi-factor products, first at least 3-factor products,
// when they're not all constants...
@@
expression E1, E2, E3;
constant C1, C2, C3;
@@

(
  kmalloc(C1 * C2 * C3, ...)
|
  kmalloc(
-	(E1) * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kmalloc(
-	(E1) * (E2) * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kmalloc(
-	(E1) * (E2) * (E3)
+	array3_size(E1, E2, E3)
  , ...)
|
  kmalloc(
-	E1 * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
)

// And then all remaining 2 factors products when they're not all constants,
// keeping sizeof() as the second factor argument.
@@
expression THING, E1, E2;
type TYPE;
constant C1, C2, C3;
@@

(
  kmalloc(sizeof(THING) * C2, ...)
|
  kmalloc(sizeof(TYPE) * C2, ...)
|
  kmalloc(C1 * C2 * C3, ...)
|
  kmalloc(C1 * C2, ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(TYPE) * (E2)
+	E2, sizeof(TYPE)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(TYPE) * E2
+	E2, sizeof(TYPE)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(THING) * (E2)
+	E2, sizeof(THING)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(THING) * E2
+	E2, sizeof(THING)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	(E1) * E2
+	E1, E2
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	(E1) * (E2)
+	E1, E2
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	E1 * E2
+	E1, E2
  , ...)
)
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      6da2ec56
    • Dan Carpenter's avatar
      test_overflow: fix an IS_ERR() vs NULL bug · 8958fd41
      Dan Carpenter authored 
      root_device_register() returns error pointers, it never returns NULL.

Fixes: ca90800a

 ("test_overflow: Add memory allocation overflow tests")
Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      8958fd41
  3. 08 Jun, 2018 6 commits
  5. 05 Jun, 2018 5 commits
    • Kees Cook's avatar
      test_overflow: Add memory allocation overflow tests · ca90800a
      Kees Cook authored 
      
Make sure that the memory allocators are behaving as expected in the face
of overflows of multiplied arguments or when using the array_size()-family
helpers.

Example output of new tests (with the expected __alloc_pages_slowpath
and vmalloc warnings about refusing giant allocations removed):

[   93.062076] test_overflow: kmalloc detected saturation
[   93.062988] test_overflow: kmalloc_node detected saturation
[   93.063818] test_overflow: kzalloc detected saturation
[   93.064539] test_overflow: kzalloc_node detected saturation
[   93.120386] test_overflow: kvmalloc detected saturation
[   93.143458] test_overflow: kvmalloc_node detected saturation
[   93.166861] test_overflow: kvzalloc detected saturation
[   93.189924] test_overflow: kvzalloc_node detected saturation
[   93.221671] test_overflow: vmalloc detected saturation
[   93.246326] test_overflow: vmalloc_node detected saturation
[   93.270260] test_overflow: vzalloc detected saturation
[   93.293824] test_overflow: vzalloc_node detected saturation
[   93.294597] test_overflow: devm_kmalloc detected saturation
[   93.295383] test_overflow: devm_kzalloc detected saturation
[   93.296217] test_overflow: all tests passed
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      ca90800a
    • Kees Cook's avatar
      test_overflow: Report test failures · 8fee81aa
      Kees Cook authored 
      
This adjusts the overflow test to report failures, and prepares to
add allocation tests.
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      8fee81aa
    • Rasmus Villemoes's avatar
      test_overflow: macrofy some more, do more tests for free · 6d334432
      Rasmus Villemoes authored 
      
Obviously a+b==b+a and a*b==b*a, but the implementation of the fallback
checks are not entirely symmetric in how they treat a and b. So we might
as well check the (b,a,r,of) tuple as well as the (a,b,r,of) one for +
and *. Rather than more copy-paste, factor out the common part to
check_one_op.
Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      6d334432
    • Rasmus Villemoes's avatar
      lib: add runtime test of check_*_overflow functions · 455a35a6
      Rasmus Villemoes authored 
      
This adds a small module for testing that the check_*_overflow
functions work as expected, whether implemented in C or using gcc
builtins.

Example output:

test_overflow: u8 : 18 tests
test_overflow: s8 : 19 tests
test_overflow: u16: 17 tests
test_overflow: s16: 17 tests
test_overflow: u32: 17 tests
test_overflow: s32: 17 tests
test_overflow: u64: 17 tests
test_overflow: s64: 21 tests
Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
[kees: add output to commit log, drop u64 tests on 32-bit]
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      455a35a6
    • Geert Uytterhoeven's avatar
      lib/vsprintf: Remove atomic-unsafe support for %pCr · 666902e4
      Geert Uytterhoeven authored 
      
"%pCr" formats the current rate of a clock, and calls clk_get_rate().
The latter obtains a mutex, hence it must not be called from atomic
context.

Remove support for this rarely-used format, as vsprintf() (and e.g.
printk()) must be callable from any context.

Any remaining out-of-tree users will start seeing the clock's name
printed instead of its rate.
Reported-by: default avatarJia-Ju Bai <baijiaju1990@gmail.com>
Fixes: 900cca29 ("lib/vsprintf: add %pC{,n,r} format specifiers for clocks")
Link: http://lkml.kernel.org/r/1527845302-12159-5-git-send-email-geert+renesas@glider.be


To: Jia-Ju Bai <baijiaju1990@gmail.com>
To: Jonathan Corbet <corbet@lwn.net>
To: Michael Turquette <mturquette@baylibre.com>
To: Stephen Boyd <sboyd@kernel.org>
To: Zhang Rui <rui.zhang@intel.com>
To: Eduardo Valentin <edubezval@gmail.com>
To: Eric Anholt <eric@anholt.net>
To: Stefan Wahren <stefan.wahren@i2se.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-clk@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: linux-serial@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-renesas-soc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: stable@vger.kernel.org # 4.1+
Signed-off-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
      666902e4
  7. 03 Jun, 2018 1 commit
  9. 31 May, 2018 1 commit
  11. 28 May, 2018 1 commit
  13. 26 May, 2018 1 commit
    • Matthew Wilcox's avatar
      idr: fix invalid ptr dereference on item delete · 7a4deea1
      Matthew Wilcox authored 
      If the radix tree underlying the IDR happens to be full and we attempt
to remove an id which is larger than any id in the IDR, we will call
__radix_tree_delete() with an uninitialised 'slot' pointer, at which
point anything could happen.  This was easiest to hit with a single
entry at id 0 and attempting to remove a non-0 id, but it could have
happened with 64 entries and attempting to remove an id >= 64.

Roman said:

  The syzcaller test boils down to opening /dev/kvm, creating an
  eventfd, and calling a couple of KVM ioctls. None of this requires
  superuser. And the result is dereferencing an uninitialized pointer
  which is likely a crash. The specific path caught by syzbot is via
  KVM_HYPERV_EVENTD ioctl which is new in 4.17. But I guess there are
  other user-triggerable paths, so cc:stable is probably justified.

Matthew added:

  We have around 250 calls to idr_remove() in the kernel today. Many of
  them pass an ID which is embedded in the object they're removing, so
  they're safe. Picking a few likely candidates:

  drivers/firewire/core-cdev.c looks unsafe; the ID comes from an ioctl.
  drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c is similar
  drivers/atm/nicstar.c could be taken down by a handcrafted packet

Link: http://lkml.kernel.org/r/20180518175025.GD6361@bombadil.infradead.org
Fixes: 0a835c4f

 ("Reimplement IDR and IDA using the radix tree")
Reported-by: <syzbot+35666cba7f0a337e2e79@syzkaller.appspotmail.com>
Debugged-by: default avatarRoman Kagan <rkagan@virtuozzo.com>
Signed-off-by: default avatarMatthew Wilcox <mawilcox@microsoft.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7a4deea1
  15. 24 May, 2018 2 commits
    • Ming Lei's avatar
      blk-mq: avoid starving tag allocation after allocating process migrates · e6fc4649
      Ming Lei authored 
      
When the allocation process is scheduled back and the mapped hw queue is
changed, fake one extra wake up on previous queue for compensating wake
up miss, so other allocations on the previous queue won't be starved.

This patch fixes one request allocation hang issue, which can be
triggered easily in case of very low nr_request.

The race is as follows:

1) 2 hw queues, nr_requests are 2, and wake_batch is one

2) there are 3 waiters on hw queue 0

3) two in-flight requests in hw queue 0 are completed, and only two
   waiters of 3 are waken up because of wake_batch, but both the two
   waiters can be scheduled to another CPU and cause to switch to hw
   queue 1

4) then the 3rd waiter will wait for ever, since no in-flight request
   is in hw queue 0 any more.

5) this patch fixes it by the fake wakeup when waiter is scheduled to
   another hw queue

Cc: <stable@vger.kernel.org>
Reviewed-by: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>

Modified commit message to make it clearer, and make it apply on
top of the 4.18 branch.
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      e6fc4649
    • Robin Murphy's avatar
      dma-debug: check scatterlist segments · 78c47830
      Robin Murphy authored 
      
Drivers/subsystems creating scatterlists for DMA should be taking care
to respect the scatter-gather limitations of the appropriate device, as
described by dma_parms. A DMA API implementation cannot feasibly split
a scatterlist into *more* entries than originally passed, so it is not
well defined what they should do when given a segment larger than the
limit they are also required to respect.

Conversely, devices which are less limited than the rather conservative
defaults, or indeed have no limitations at all (e.g. GPUs with their own
internal MMU), should be encouraged to set appropriate dma_parms, as
they may get more efficient DMA mapping performance out of it.
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      78c47830
  17. 23 May, 2018 1 commit
  19. 19 May, 2018 4 commits
    • Christoph Hellwig's avatar
      dma-mapping: provide a generic dma-noncoherent implementation · 782e6769
      Christoph Hellwig authored 
      
Add a new dma_map_ops implementation that uses dma-direct for the
address mapping of streaming mappings, and which requires arch-specific
implemenations of coherent allocate/free.

Architectures have to provide flushing helpers to ownership trasnfers
to the device and/or CPU, and can provide optional implementations of
the coherent mmap functionality, and the cache_flush routines for
non-coherent long term allocations.
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Tested-by: default avatarAlexey Brodkin <abrodkin@synopsys.com>
Acked-by: default avatarVineet Gupta <vgupta@synopsys.com>
      782e6769
    • Christoph Hellwig's avatar
      dma-mapping: simplify Kconfig dependencies · 35ddb69c
      Christoph Hellwig authored 
      
ARCH_DMA_ADDR_T_64BIT is always true for 64-bit architectures now, so we
can skip the clause requiring it.  'n' is the default default, so no need
to explicitly state it.
Tested-by: default avatarAlexey Brodkin <abrodkin@synopsys.com>
Acked-by: default avatarVineet Gupta <vgupta@synopsys.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      35ddb69c
    • Ross Zwisler's avatar
      radix tree: fix multi-order iteration race · 9f418224
      Ross Zwisler authored 
      Fix a race in the multi-order iteration code which causes the kernel to
hit a GP fault.  This was first seen with a production v4.15 based
kernel (4.15.6-300.fc27.x86_64) utilizing a DAX workload which used
order 9 PMD DAX entries.

The race has to do with how we tear down multi-order sibling entries
when we are removing an item from the tree.  Remember for example that
an order 2 entry looks like this:

  struct radix_tree_node.slots[] = [entry][sibling][sibling][sibling]

where 'entry' is in some slot in the struct radix_tree_node, and the
three slots following 'entry' contain sibling pointers which point back
to 'entry.'

When we delete 'entry' from the tree, we call :

  radix_tree_delete()
    radix_tree_delete_item()
      __radix_tree_delete()
        replace_slot()

replace_slot() first removes the siblings in order from the first to the
last, then at then replaces 'entry' with NULL.  This means that for a
brief period of time we end up with one or more of the siblings removed,
so:

  struct radix_tree_node.slots[] = [entry][NULL][sibling][sibling]

This causes an issue if you have a reader iterating over the slots in
the tree via radix_tree_for_each_slot() while only under
rcu_read_lock()/rcu_read_unlock() protection.  This is a common case in
mm/filemap.c.

The issue is that when __radix_tree_next_slot() => skip_siblings() tries
to skip over the sibling entries in the slots, it currently does so with
an exact match on the slot directly preceding our current slot.
Normally this works:

                                      V preceding slot
  struct radix_tree_node.slots[] = [entry][sibling][sibling][sibling]
                                              ^ current slot

This lets you find the first sibling, and you skip them all in order.

But in the case where one of the siblings is NULL, that slot is skipped
and then our sibling detection is interrupted:

                                             V preceding slot
  struct radix_tree_node.slots[] = [entry][NULL][sibling][sibling]
                                                    ^ current slot

This means that the sibling pointers aren't recognized since they point
all the way back to 'entry', so we think that they are normal internal
radix tree pointers.  This causes us to think we need to walk down to a
struct radix_tree_node starting at the address of 'entry'.

In a real running kernel this will crash the thread with a GP fault when
you try and dereference the slots in your broken node starting at
'entry'.

We fix this race by fixing the way that skip_siblings() detects sibling
nodes.  Instead of testing against the preceding slot we instead look
for siblings via is_sibling_entry() which compares against the position
of the struct radix_tree_node.slots[] array.  This ensures that sibling
entries are properly identified, even if they are no longer contiguous
with the 'entry' they point to.

Link: http://lkml.kernel.org/r/20180503192430.7582-6-ross.zwisler@linux.intel.com
Fixes: 148deab2

 ("radix-tree: improve multiorder iterators")
Signed-off-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
Reported-by: default avatarCR, Sapthagirish <sapthagirish.cr@intel.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9f418224
    • Matthew Wilcox's avatar
      lib/test_bitmap.c: fix bitmap optimisation tests to report errors correctly · 1e3054b9
      Matthew Wilcox authored 
      I had neglected to increment the error counter when the tests failed,
which made the tests noisy when they fail, but not actually return an
error code.

Link: http://lkml.kernel.org/r/20180509114328.9887-1-mpe@ellerman.id.au
Fixes: 3cc78125

 ("lib/test_bitmap.c: add optimisation tests")
Signed-off-by: default avatarMatthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Reported-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Tested-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Cc: Yury Norov <ynorov@caviumnetworks.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: <stable@vger.kernel.org>	[4.13+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1e3054b9
  21. 16 May, 2018 1 commit
    • Steven Rostedt (VMware)'s avatar
      vsprintf: Replace memory barrier with static_key for random_ptr_key update · 85f4f12d
      Steven Rostedt (VMware) authored 
      Reviewing Tobin's patches for getting pointers out early before
entropy has been established, I noticed that there's a lone smp_mb() in
the code. As with most lone memory barriers, this one appears to be
incorrectly used.

We currently basically have this:

	get_random_bytes(&ptr_key, sizeof(ptr_key));
	/*
	 * have_filled_random_ptr_key==true is dependent on get_random_bytes().
	 * ptr_to_id() needs to see have_filled_random_ptr_key==true
	 * after get_random_bytes() returns.
	 */
	smp_mb();
	WRITE_ONCE(have_filled_random_ptr_key, true);

And later we have:

	if (unlikely(!have_filled_random_ptr_key))
		return string(buf, end, "(ptrval)", spec);

/* Missing memory barrier here. */

	hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key);

As the CPU can perform speculative loads, we could have a situation
with the following:

	CPU0				CPU1
	----				----
				   load ptr_key = 0
   store ptr_key = random
   smp_mb()
   store have_filled_random_ptr_key

				   load have_filled_random_ptr_key = true

				    BAD BAD BAD! (you're so bad!)

Because nothing prevents CPU1 from loading ptr_key before loading
have_filled_random_ptr_key.

But this race is very unlikely, but we can't keep an incorrect smp_mb() in
place. Instead, replace the have_filled_random_ptr_key with a static_branch
not_filled_random_ptr_key, that is initialized to true and changed to false
when we get enough entropy. If the update happens in early boot, the
static_key is updated immediately, otherwise it will have to wait till
entropy is filled and this happens in an interrupt handler which can't
enable a static_key, as that requires a preemptible context. In that case, a
work_queue is used to enable it, as entropy already took too long to
establish in the first place waiting a little more shouldn't hurt anything.

The benefit of using the static key is that the unlikely branch in
vsprintf() now becomes a nop.

Link: http://lkml.kernel.org/r/20180515100558.21df515e@gandalf.local.home

Cc: stable@vger.kernel.org
Fixes: ad67b74d

 ("printk: hash addresses printed with %p")
Acked-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
      85f4f12d
  23. 15 May, 2018 1 commit
  25. 14 May, 2018 1 commit
    • Jens Axboe's avatar
      sbitmap: fix race in wait batch accounting · c854ab57
      Jens Axboe authored 
      If we have multiple callers of sbq_wake_up(), we can end up in a
situation where the wait_cnt will continually go more and more
negative. Consider the case where our wake batch is 1, hence
wait_cnt will start out as 1.

wait_cnt == 1

CPU0				CPU1
atomic_dec_return(), cnt == 0
				atomic_dec_return(), cnt == -1
				cmpxchg(-1, 0) (succeeds)
				[wait_cnt now 0]
cmpxchg(0, 1) (fails)

This ends up with wait_cnt being 0, we'll wakeup immediately
next time. Going through the same loop as above again, and
we'll have wait_cnt -1.

For the case where we have a larger wake batch, the only
difference is that the starting point will be higher. We'll
still end up with continually smaller batch wakeups, which
defeats the purpose of the rolling wakeups.

Always reset the wait_cnt to the batch value. Then it doesn't
matter who wins the race. But ensure that whomever does win
the race is the one that increments the ws index and wakes up
our batch count, loser gets to call __sbq_wake_up() again to
account his wakeups towards the next active wait state index.

Fixes: 6c0ca7ae

 ("sbitmap: fix wakeup hang after sbq resize")
Reviewed-by: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      c854ab57
  27. 12 May, 2018 2 commits
  29. 10 May, 2018 2 commits
  31. 09 May, 2018 9 commits

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