linux-stable.git/lib, branch v4.4.185

lib/mpi: Fix karactx leak in mpi_powm

2019-07-10T07:56:43+00:00

commit c8ea9fce2baf7b643384f36f29e4194fa40d33a6 upstream.

Sometimes mpi_powm will leak karactx because a memory allocation
failure causes a bail-out that skips the freeing of karactx.  This
patch moves the freeing of karactx to the end of the function like
everything else so that it can't be skipped.

Reported-by: syzbot+f7baccc38dcc1e094e77@syzkaller.appspotmail.com
Fixes: cdec9cb5167a ("crypto: GnuPG based MPI lib - source files...")
Cc: 
Signed-off-by: Herbert Xu 
Reviewed-by: Eric Biggers 
Signed-off-by: Herbert Xu 
Signed-off-by: Greg Kroah-Hartman

mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions

2019-06-11T10:23:56+00:00

[ Upstream commit 29da93fea3ea39ab9b12270cc6be1b70ef201c9e ]

Randy reported objtool triggered on his (GCC-7.4) build:

  lib/strncpy_from_user.o: warning: objtool: strncpy_from_user()+0x315: call to __ubsan_handle_add_overflow() with UACCESS enabled
  lib/strnlen_user.o: warning: objtool: strnlen_user()+0x337: call to __ubsan_handle_sub_overflow() with UACCESS enabled

This is due to UBSAN generating signed-overflow-UB warnings where it
should not. Prior to GCC-8 UBSAN ignored -fwrapv (which the kernel
uses through -fno-strict-overflow).

Make the functions use 'unsigned long' throughout.

Reported-by: Randy Dunlap 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Randy Dunlap  # build-tested
Acked-by: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: luto@kernel.org
Link: http://lkml.kernel.org/r/20190424072208.754094071@infradead.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

lib/div64.c: off by one in shift

2019-04-27T07:33:59+00:00

[ Upstream commit cdc94a37493135e355dfc0b0e086d84e3eadb50d ]

fls counts bits starting from 1 to 32 (returns 0 for zero argument).  If
we add 1 we shift right one bit more and loose precision from divisor,
what cause function incorect results with some numbers.

Corrected code was tested in user-space, see bugzilla:
   https://bugzilla.kernel.org/show_bug.cgi?id=202391

Link: http://lkml.kernel.org/r/1548686944-11891-1-git-send-email-sgruszka@redhat.com
Fixes: 658716d19f8f ("div64_u64(): improve precision on 32bit platforms")
Signed-off-by: Stanislaw Gruszka 
Reported-by: Siarhei Volkau 
Tested-by: Siarhei Volkau 
Acked-by: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

lib/string.c: implement a basic bcmp

2019-04-27T07:33:54+00:00

[ Upstream commit 5f074f3e192f10c9fade898b9b3b8812e3d83342 ]

A recent optimization in Clang (r355672) lowers comparisons of the
return value of memcmp against zero to comparisons of the return value
of bcmp against zero.  This helps some platforms that implement bcmp
more efficiently than memcmp.  glibc simply aliases bcmp to memcmp, but
an optimized implementation is in the works.

This results in linkage failures for all targets with Clang due to the
undefined symbol.  For now, just implement bcmp as a tailcail to memcmp
to unbreak the build.  This routine can be further optimized in the
future.

Other ideas discussed:

 * A weak alias was discussed, but breaks for architectures that define
   their own implementations of memcmp since aliases to declarations are
   not permitted (only definitions). Arch-specific memcmp
   implementations typically declare memcmp in C headers, but implement
   them in assembly.

 * -ffreestanding also is used sporadically throughout the kernel.

 * -fno-builtin-bcmp doesn't work when doing LTO.

Link: https://bugs.llvm.org/show_bug.cgi?id=41035
Link: https://code.woboq.org/userspace/glibc/string/memcmp.c.html#bcmp
Link: https://github.com/llvm/llvm-project/commit/8e16d73346f8091461319a7dfc4ddd18eedcff13
Link: https://github.com/ClangBuiltLinux/linux/issues/416
Link: http://lkml.kernel.org/r/20190313211335.165605-1-ndesaulniers@google.com
Signed-off-by: Nick Desaulniers 
Reported-by: Nathan Chancellor 
Reported-by: Adhemerval Zanella 
Suggested-by: Arnd Bergmann 
Suggested-by: James Y Knight 
Suggested-by: Masahiro Yamada 
Suggested-by: Nathan Chancellor 
Suggested-by: Rasmus Villemoes 
Acked-by: Steven Rostedt (VMware) 
Reviewed-by: Nathan Chancellor 
Tested-by: Nathan Chancellor 
Reviewed-by: Masahiro Yamada 
Reviewed-by: Andy Shevchenko 
Cc: David Laight 
Cc: Rasmus Villemoes 
Cc: Namhyung Kim 
Cc: Greg Kroah-Hartman 
Cc: Alexander Shishkin 
Cc: Dan Williams 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

ARM: 8833/1: Ensure that NEON code always compiles with Clang

2019-04-27T07:33:51+00:00

[ Upstream commit de9c0d49d85dc563549972edc5589d195cd5e859 ]

While building arm32 allyesconfig, I ran into the following errors:

  arch/arm/lib/xor-neon.c:17:2: error: You should compile this file with
  '-mfloat-abi=softfp -mfpu=neon'

  In file included from lib/raid6/neon1.c:27:
  /home/nathan/cbl/prebuilt/lib/clang/8.0.0/include/arm_neon.h:28:2:
  error: "NEON support not enabled"

Building V=1 showed NEON_FLAGS getting passed along to Clang but
__ARM_NEON__ was not getting defined. Ultimately, it boils down to Clang
only defining __ARM_NEON__ when targeting armv7, rather than armv6k,
which is the '-march' value for allyesconfig.

>From lib/Basic/Targets/ARM.cpp in the Clang source:

  // This only gets set when Neon instructions are actually available, unlike
  // the VFP define, hence the soft float and arch check. This is subtly
  // different from gcc, we follow the intent which was that it should be set
  // when Neon instructions are actually available.
  if ((FPU & NeonFPU) && !SoftFloat && ArchVersion >= 7) {
    Builder.defineMacro("__ARM_NEON", "1");
    Builder.defineMacro("__ARM_NEON__");
    // current AArch32 NEON implementations do not support double-precision
    // floating-point even when it is present in VFP.
    Builder.defineMacro("__ARM_NEON_FP",
                        "0x" + Twine::utohexstr(HW_FP & ~HW_FP_DP));
  }

Ard Biesheuvel recommended explicitly adding '-march=armv7-a' at the
beginning of the NEON_FLAGS definitions so that __ARM_NEON__ always gets
definined by Clang. This doesn't functionally change anything because
that code will only run where NEON is supported, which is implicitly
armv7.

Link: https://github.com/ClangBuiltLinux/linux/issues/287

Suggested-by: Ard Biesheuvel 
Signed-off-by: Nathan Chancellor 
Acked-by: Nicolas Pitre 
Reviewed-by: Nick Desaulniers 
Reviewed-by: Stefan Agner 
Signed-off-by: Russell King 
Signed-off-by: Sasha Levin

kprobes: Prohibit probing on bsearch()

2019-04-27T07:33:51+00:00

[ Upstream commit 02106f883cd745523f7766d90a739f983f19e650 ]

Since kprobe breakpoing handler is using bsearch(), probing on this
routine can cause recursive breakpoint problem.

int3
 ->do_int3()
   ->ftrace_int3_handler()
     ->ftrace_location()
       ->ftrace_location_range()
         ->bsearch() -> int3

Prohibit probing on bsearch().

Signed-off-by: Andrea Righi 
Acked-by: Masami Hiramatsu 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Mathieu Desnoyers 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/154998813406.31052.8791425358974650922.stgit@devbox
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

lib/int_sqrt: optimize initial value compute

2019-04-27T07:33:47+00:00

commit f8ae107eef209bff29a5816bc1aad40d5cd69a80 upstream.

The initial value (@m) compute is:

	m = 1UL << (BITS_PER_LONG - 2);
	while (m > x)
		m >>= 2;

Which is a linear search for the highest even bit smaller or equal to @x
We can implement this using a binary search using __fls() (or better when
its hardware implemented).

	m = 1UL << (__fls(x) & ~1UL);

Especially for small values of @x; which are the more common arguments
when doing a CDF on idle times; the linear search is near to worst case,
while the binary search of __fls() is a constant 6 (or 5 on 32bit)
branches.

      cycles:                 branches:              branch-misses:

PRE:

hot:   43.633557 +- 0.034373  45.333132 +- 0.002277  0.023529 +- 0.000681
cold: 207.438411 +- 0.125840  45.333132 +- 0.002277  6.976486 +- 0.004219

SOFTWARE FLS:

hot:   29.576176 +- 0.028850  26.666730 +- 0.004511  0.019463 +- 0.000663
cold: 165.947136 +- 0.188406  26.666746 +- 0.004511  6.133897 +- 0.004386

HARDWARE FLS:

hot:   24.720922 +- 0.025161  20.666784 +- 0.004509  0.020836 +- 0.000677
cold: 132.777197 +- 0.127471  20.666776 +- 0.004509  5.080285 +- 0.003874

Averages computed over all values <128k using a LFSR to generate order.
Cold numbers have a LFSR based branch trace buffer 'confuser' ran between
each int_sqrt() invocation.

Link: http://lkml.kernel.org/r/20171020164644.936577234@infradead.org
Signed-off-by: Peter Zijlstra (Intel) 
Suggested-by: Joe Perches 
Acked-by: Will Deacon 
Acked-by: Linus Torvalds 
Cc: Anshul Garg 
Cc: Davidlohr Bueso 
Cc: David Miller 
Cc: Ingo Molnar 
Cc: Kees Cook 
Cc: Matthew Wilcox 
Cc: Michael Davidson 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Cc: Joe Perches 
Signed-off-by: Greg Kroah-Hartman

lib/int_sqrt: optimize small argument

2019-04-03T04:23:19+00:00

commit 3f3295709edea6268ff1609855f498035286af73 upstream.

The current int_sqrt() computation is sub-optimal for the case of small
@x.  Which is the interesting case when we're going to do cumulative
distribution functions on idle times, which we assume to be a random
variable, where the target residency of the deepest idle state gives an
upper bound on the variable (5e6ns on recent Intel chips).

In the case of small @x, the compute loop:

	while (m != 0) {
		b = y + m;
		y >>= 1;

		if (x >= b) {
			x -= b;
			y += m;
		}
		m >>= 2;
	}

can be reduced to:

	while (m > x)
		m >>= 2;

Because y==0, b==m and until x>=m y will remain 0.

And while this is computationally equivalent, it runs much faster
because there's less code, in particular less branches.

      cycles:                 branches:              branch-misses:

OLD:

hot:   45.109444 +- 0.044117  44.333392 +- 0.002254  0.018723 +- 0.000593
cold: 187.737379 +- 0.156678  44.333407 +- 0.002254  6.272844 +- 0.004305

PRE:

hot:   67.937492 +- 0.064124  66.999535 +- 0.000488  0.066720 +- 0.001113
cold: 232.004379 +- 0.332811  66.999527 +- 0.000488  6.914634 +- 0.006568

POST:

hot:   43.633557 +- 0.034373  45.333132 +- 0.002277  0.023529 +- 0.000681
cold: 207.438411 +- 0.125840  45.333132 +- 0.002277  6.976486 +- 0.004219

Averages computed over all values <128k using a LFSR to generate order.
Cold numbers have a LFSR based branch trace buffer 'confuser' ran between
each int_sqrt() invocation.

Link: http://lkml.kernel.org/r/20171020164644.876503355@infradead.org
Fixes: 30493cc9dddb ("lib/int_sqrt.c: optimize square root algorithm")
Signed-off-by: Peter Zijlstra (Intel) 
Suggested-by: Anshul Garg 
Acked-by: Linus Torvalds 
Cc: Davidlohr Bueso 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Will Deacon 
Cc: Joe Perches 
Cc: David Miller 
Cc: Matthew Wilcox 
Cc: Kees Cook 
Cc: Michael Davidson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Arnd Bergmann 
Signed-off-by: Greg Kroah-Hartman

assoc_array: Fix shortcut creation

2019-03-23T07:44:33+00:00

[ Upstream commit bb2ba2d75a2d673e76ddaf13a9bd30d6a8b1bb08 ]

Fix the creation of shortcuts for which the length of the index key value
is an exact multiple of the machine word size.  The problem is that the
code that blanks off the unused bits of the shortcut value malfunctions if
the number of bits in the last word equals machine word size.  This is due
to the "<<" operator being given a shift of zero in this case, and so the
mask that should be all zeros is all ones instead.  This causes the
subsequent masking operation to clear everything rather than clearing
nothing.

Ordinarily, the presence of the hash at the beginning of the tree index key
makes the issue very hard to test for, but in this case, it was encountered
due to a development mistake that caused the hash output to be either 0
(keyring) or 1 (non-keyring) only.  This made it susceptible to the
keyctl/unlink/valid test in the keyutils package.

The fix is simply to skip the blanking if the shift would be 0.  For
example, an index key that is 64 bits long would produce a 0 shift and thus
a 'blank' of all 1s.  This would then be inverted and AND'd onto the
index_key, incorrectly clearing the entire last word.

Fixes: 3cb989501c26 ("Add a generic associative array implementation.")
Signed-off-by: David Howells 
Signed-off-by: James Morris 
Signed-off-by: Sasha Levin

test_hexdump: use memcpy instead of strncpy

2019-02-20T09:13:14+00:00

commit b1286ed7158e9b62787508066283ab0b8850b518 upstream.

New versions of gcc reasonably warn about the odd pattern of

	strncpy(p, q, strlen(q));

which really doesn't make sense: the strncpy() ends up being just a slow
and odd way to write memcpy() in this case.

Apparently there was a patch for this floating around earlier, but it
got lost.

Acked-again-by: Andy Shevchenko 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman