linux-stable.git/tools/testing/selftests/vm, branch linux-5.14.y

tools/testing/selftests/vm/split_huge_page_test.c: fix application of sizeof to pointer

2021-11-17T10:03:32+00:00

[ Upstream commit 9c7516d669e68e94e17203469a873ff5d1d3a41a ]

The coccinelle check report:

  ./tools/testing/selftests/vm/split_huge_page_test.c:344:36-42:
  ERROR: application of sizeof to pointer

Use "strlen" to fix it.

Link: https://lkml.kernel.org/r/20211012030116.184027-1-davidcomponentone@gmail.com
Signed-off-by: David Yang 
Reported-by: Zeal Robot 
Cc: Zi Yan 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

mm/userfaultfd: selftests: fix memory corruption with thp enabled

2021-10-27T07:59:42+00:00

commit 8913970c19915bbe773d97d42989cd85b7fdc098 upstream.

In RHEL's gating selftests we've encountered memory corruption in the
uffd event test even with upstream kernel:

        # ./userfaultfd anon 128 4
        nr_pages: 32768, nr_pages_per_cpu: 32768
        bounces: 3, mode: rnd racing read, userfaults: 6240 missing (6240) 14729 wp (14729)
        bounces: 2, mode: racing read, userfaults: 1444 missing (1444) 28877 wp (28877)
        bounces: 1, mode: rnd read, userfaults: 6055 missing (6055) 14699 wp (14699)
        bounces: 0, mode: read, userfaults: 82 missing (82) 25196 wp (25196)
        testing uffd-wp with pagemap (pgsize=4096): done
        testing uffd-wp with pagemap (pgsize=2097152): done
        testing events (fork, remap, remove): ERROR: nr 32427 memory corruption 0 1 (errno=0, line=963)
        ERROR: faulting process failed (errno=0, line=1117)

It can be easily reproduced when global thp enabled, which is the
default for RHEL.

It's also known as a side effect of commit 0db282ba2c12 ("selftest: use
mmap instead of posix_memalign to allocate memory", 2021-07-23), which
is imho right itself on using mmap() to make sure the addresses will be
untagged even on arm.

The problem is, for each test we allocate buffers using two
allocate_area() calls.  We assumed these two buffers won't affect each
other, however they could, because mmap() could have found that the two
buffers are near each other and having the same VMA flags, so they got
merged into one VMA.

It won't be a big problem if thp is not enabled, but when thp is
agressively enabled it means when initializing the src buffer it could
accidentally setup part of the dest buffer too when there's a shared THP
that overlaps the two regions.  Then some of the dest buffer won't be
able to be trapped by userfaultfd missing mode, then it'll cause memory
corruption as described.

To fix it, do release_pages() after initializing the src buffer.

Since the previous two release_pages() calls are after
uffd_test_ctx_clear() which will unmap all the buffers anyway (which is
stronger than release pages; as unmap() also tear town pgtables), drop
them as they shouldn't really be anything useful.

We can mark the Fixes tag upon 0db282ba2c12 as it's reported to only
happen there, however the real "Fixes" IMHO should be 8ba6e8640844, as
before that commit we'll always do explicit release_pages() before
registration of uffd, and 8ba6e8640844 changed that logic by adding
extra unmap/map and we didn't release the pages at the right place.
Meanwhile I don't have a solid glue anyway on whether posix_memalign()
could always avoid triggering this bug, hence it's safer to attach this
fix to commit 8ba6e8640844.

Link: https://lkml.kernel.org/r/20210923232512.210092-1-peterx@redhat.com
Fixes: 8ba6e8640844 ("userfaultfd/selftests: reinitialize test context in each test")
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1994931
Signed-off-by: Peter Xu 
Reported-by: Li Wang 
Tested-by: Li Wang 
Reviewed-by: Axel Rasmussen 
Cc: Andrea Arcangeli 
Cc: Nadav Amit 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

selftest: use mmap instead of posix_memalign to allocate memory

2021-07-24T00:43:28+00:00

This test passes pointers obtained from anon_allocate_area to the
userfaultfd and mremap APIs.  This causes a problem if the system
allocator returns tagged pointers because with the tagged address ABI
the kernel rejects tagged addresses passed to these APIs, which would
end up causing the test to fail.  To make this test compatible with such
system allocators, stop using the system allocator to allocate memory in
anon_allocate_area, and instead just use mmap.

Link: https://lkml.kernel.org/r/20210714195437.118982-3-pcc@google.com
Link: https://linux-review.googlesource.com/id/Icac91064fcd923f77a83e8e133f8631c5b8fc241
Fixes: c47174fc362a ("userfaultfd: selftest")
Co-developed-by: Lokesh Gidra 
Signed-off-by: Lokesh Gidra 
Signed-off-by: Peter Collingbourne 
Reviewed-by: Catalin Marinas 
Cc: Vincenzo Frascino 
Cc: Dave Martin 
Cc: Will Deacon 
Cc: Andrea Arcangeli 
Cc: Alistair Delva 
Cc: William McVicker 
Cc: Evgenii Stepanov 
Cc: Mitch Phillips 
Cc: Andrey Konovalov 
Cc: 	[5.4]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftest/mremap_test: avoid crash with static build

2021-07-08T18:48:22+00:00

With a large mmap map size, we can overlap with the text area and using
MAP_FIXED results in unmapping that area.  Switch to MAP_FIXED_NOREPLACE
and handle the EEXIST error.

Link: https://lkml.kernel.org/r/20210616045239.370802-3-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V 
Reviewed-by: Kalesh Singh 
Cc: Christophe Leroy 
Cc: Hugh Dickins 
Cc: Joel Fernandes 
Cc: Kirill A. Shutemov 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Stephen Rothwell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftest/mremap_test: update the test to handle pagesize other than 4K

2021-07-08T18:48:22+00:00

Patch series "mrermap fixes", v2.

This patch (of 6):

Instead of hardcoding 4K page size fetch it using sysconf().  For the
performance measurements test still assume 2M and 1G are hugepage sizes.

Link: https://lkml.kernel.org/r/20210616045239.370802-1-aneesh.kumar@linux.ibm.com
Link: https://lkml.kernel.org/r/20210616045239.370802-2-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V 
Reviewed-by: Kalesh Singh 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Joel Fernandes 
Cc: Christophe Leroy 
Cc: Kirill A. Shutemov 
Cc: Hugh Dickins 
Cc: Kirill A. Shutemov 
Cc: Stephen Rothwell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

secretmem: test: add basic selftest for memfd_secret(2)

2021-07-08T18:48:21+00:00

The test verifies that file descriptor created with memfd_secret does not
allow read/write operations, that secret memory mappings respect
RLIMIT_MEMLOCK and that remote accesses with process_vm_read() and
ptrace() to the secret memory fail.

Link: https://lkml.kernel.org/r/20210518072034.31572-8-rppt@kernel.org
Signed-off-by: Mike Rapoport 
Acked-by: James Bottomley 
Cc: Alexander Viro 
Cc: Andy Lutomirski 
Cc: Arnd Bergmann 
Cc: Borislav Petkov 
Cc: Catalin Marinas 
Cc: Christopher Lameter 
Cc: Dan Williams 
Cc: Dave Hansen 
Cc: David Hildenbrand 
Cc: Elena Reshetova 
Cc: Hagen Paul Pfeifer 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: James Bottomley 
Cc: "Kirill A. Shutemov" 
Cc: Mark Rutland 
Cc: Matthew Wilcox 
Cc: Michael Kerrisk 
Cc: Palmer Dabbelt 
Cc: Palmer Dabbelt 
Cc: Paul Walmsley 
Cc: Peter Zijlstra 
Cc: Rick Edgecombe 
Cc: Roman Gushchin 
Cc: Shakeel Butt 
Cc: Shuah Khan 
Cc: Thomas Gleixner 
Cc: Tycho Andersen 
Cc: Will Deacon 
Cc: kernel test robot 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftests/vm/pkeys: exercise x86 XSAVE init state

2021-07-01T18:06:06+00:00

On x86, there is a set of instructions used to save and restore register
state collectively known as the XSAVE architecture.  There are about a
dozen different features managed with XSAVE.  The protection keys
register, PKRU, is one of those features.

The hardware optimizes XSAVE by tracking when the state has not changed
from its initial (init) state.  In this case, it can avoid the cost of
writing state to memory (it would usually just be a bunch of 0's).

When the pkey register is 0x0 the hardware optionally choose to track the
register as being in the init state (optimize away the writes).  AMD CPUs
do this more aggressively compared to Intel.

On x86, PKRU is rarely in its (very permissive) init state.  Instead, the
value defaults to something very restrictive.  It is not surprising that
bugs have popped up in the rare cases when PKRU reaches its init state.

Add a protection key selftest which gets the protection keys register into
its init state in a way that should work on Intel and AMD.  Then, do a
bunch of pkey register reads to watch for inadvertent changes.

This adds "-mxsave" to CFLAGS for all the x86 vm selftests in order to
allow use of the XSAVE instruction __builtin functions.  This will make
the builtins available on all of the vm selftests, but is expected to be
harmless.

Link: https://lkml.kernel.org/r/20210611164202.1849B712@viggo.jf.intel.com
Signed-off-by: Dave Hansen 
Signed-off-by: Thomas Gleixner 
Tested-by: Aneesh Kumar K.V 
Cc: Ram Pai 
Cc: Sandipan Das 
Cc: Florian Weimer 
Cc: "Desnes A. Nunes do Rosario" 
Cc: Ingo Molnar 
Cc: Thiago Jung Bauermann 
Cc: Michael Ellerman 
Cc: Michal Hocko 
Cc: Michal Suchanek 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftests/vm/pkeys: refill shadow register after implicit kernel write

2021-07-01T18:06:06+00:00

The pkey test code keeps a "shadow" of the pkey register around.  This
ensures that any bugs which might write to the register can be caught more
quickly.

Generally, userspace has a good idea when the kernel is going to write to
the register.  For instance, alloc_pkey() is passed a permission mask.
The caller of alloc_pkey() can update the shadow based on the return value
and the mask.

But, the kernel can also modify the pkey register in a more sneaky way.
For mprotect(PROT_EXEC) mappings, the kernel will allocate a pkey and
write the pkey register to create an execute-only mapping.  The kernel
never tells userspace what key it uses for this.

This can cause the test to fail with messages like:

	protection_keys_64.2: pkey-helpers.h:132: _read_pkey_reg: Assertion `pkey_reg == shadow_pkey_reg' failed.

because the shadow was not updated with the new kernel-set value.

Forcibly update the shadow value immediately after an mprotect().

Link: https://lkml.kernel.org/r/20210611164200.EF76AB73@viggo.jf.intel.com
Fixes: 6af17cf89e99 ("x86/pkeys/selftests: Add PROT_EXEC test")
Signed-off-by: Dave Hansen 
Signed-off-by: Thomas Gleixner 
Tested-by: Aneesh Kumar K.V 
Cc: Ram Pai 
Cc: Sandipan Das 
Cc: Florian Weimer 
Cc: "Desnes A. Nunes do Rosario" 
Cc: Ingo Molnar 
Cc: Thiago Jung Bauermann 
Cc: Michael Ellerman 
Cc: Michal Hocko 
Cc: Michal Suchanek 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftests/vm/pkeys: handle negative sys_pkey_alloc() return code

2021-07-01T18:06:06+00:00

The alloc_pkey() sefltest function wraps the sys_pkey_alloc() system call.
On success, it updates its "shadow" register value because
sys_pkey_alloc() updates the real register.

But, the success check is wrong.  pkey_alloc() considers any non-zero
return code to indicate success where the pkey register will be modified.
This fails to take negative return codes into account.

Consider only a positive return value as a successful call.

Link: https://lkml.kernel.org/r/20210611164157.87AB4246@viggo.jf.intel.com
Fixes: 5f23f6d082a9 ("x86/pkeys: Add self-tests")
Reported-by: Thomas Gleixner 
Signed-off-by: Dave Hansen 
Tested-by: Aneesh Kumar K.V 
Cc: Ram Pai 
Cc: Sandipan Das 
Cc: Florian Weimer 
Cc: "Desnes A. Nunes do Rosario" 
Cc: Ingo Molnar 
Cc: Thiago Jung Bauermann 
Cc: Michael Ellerman 
Cc: Michal Hocko 
Cc: Michal Suchanek 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftests/vm/pkeys: fix alloc_random_pkey() to make it really, really random

2021-07-01T18:06:06+00:00

Patch series "selftests/vm/pkeys: Bug fixes and a new test".

There has been a lot of activity on the x86 front around the XSAVE
architecture which is used to context-switch processor state (among other
things).  In addition, AMD has recently joined the protection keys club by
adding processor support for PKU.

The AMD implementation helped uncover a kernel bug around the PKRU "init
state", which actually applied to Intel's implementation but was just
harder to hit.  This series adds a test which is expected to help find
this class of bug both on AMD and Intel.  All the work around pkeys on x86
also uncovered a few bugs in the selftest.

This patch (of 4):

The "random" pkey allocation code currently does the good old:

	srand((unsigned int)time(NULL));

*But*, it unfortunately does this on every random pkey allocation.

There may be thousands of these a second.  time() has a one second
resolution.  So, each time alloc_random_pkey() is called, the PRNG is
*RESET* to time().  This is nasty.  Normally, if you do:

	srand();
	foo = rand();
	bar = rand();

You'll be quite guaranteed that 'foo' and 'bar' are different.  But, if
you do:

	srand(1);
	foo = rand();
	srand(1);
	bar = rand();

You are quite guaranteed that 'foo' and 'bar' are the *SAME*.  The recent
"fix" effectively forced the test case to use the same "random" pkey for
the whole test, unless the test run crossed a second boundary.

Only run srand() once at program startup.

This explains some very odd and persistent test failures I've been seeing.

Link: https://lkml.kernel.org/r/20210611164153.91B76FB8@viggo.jf.intel.com
Link: https://lkml.kernel.org/r/20210611164155.192D00FF@viggo.jf.intel.com
Fixes: 6e373263ce07 ("selftests/vm/pkeys: fix alloc_random_pkey() to make it really random")
Signed-off-by: Dave Hansen 
Signed-off-by: Thomas Gleixner 
Tested-by: Aneesh Kumar K.V 
Cc: Ram Pai 
Cc: Sandipan Das 
Cc: Florian Weimer 
Cc: "Desnes A. Nunes do Rosario" 
Cc: Ingo Molnar 
Cc: Thiago Jung Bauermann 
Cc: Michael Ellerman 
Cc: Michal Hocko 
Cc: Michal Suchanek 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds