queue-5.0/arm64-compat-reduce-address-limit.patch

   1 From d263119387de9975d2acba1dfd3392f7c5979c18 Mon Sep 17 00:00:00 2001
   2 From: Vincenzo Frascino <vincenzo.frascino@arm.com>
   3 Date: Mon, 1 Apr 2019 12:30:14 +0100
   4 Subject: arm64: compat: Reduce address limit
   5
   6 From: Vincenzo Frascino <vincenzo.frascino@arm.com>
   7
   8 commit d263119387de9975d2acba1dfd3392f7c5979c18 upstream.
   9
  10 Currently, compat tasks running on arm64 can allocate memory up to
  11 TASK_SIZE_32 (UL(0x100000000)).
  12
  13 This means that mmap() allocations, if we treat them as returning an
  14 array, are not compliant with the sections 6.5.8 of the C standard
  15 (C99) which states that: "If the expression P points to an element of
  16 an array object and the expression Q points to the last element of the
  17 same array object, the pointer expression Q+1 compares greater than P".
  18
  19 Redefine TASK_SIZE_32 to address the issue.
  20
  21 Cc: Catalin Marinas <catalin.marinas@arm.com>
  22 Cc: Will Deacon <will.deacon@arm.com>
  23 Cc: Jann Horn <jannh@google.com>
  24 Cc: <stable@vger.kernel.org>
  25 Reported-by: Jann Horn <jannh@google.com>
  26 Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
  27 [will: fixed typo in comment]
  28 Signed-off-by: Will Deacon <will.deacon@arm.com>
  29 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  30
  31 ---
  32  arch/arm64/include/asm/processor.h |    8 ++++++++
  33  1 file changed, 8 insertions(+)
  34
  35 --- a/arch/arm64/include/asm/processor.h
  36 +++ b/arch/arm64/include/asm/processor.h
  37 @@ -57,7 +57,15 @@
  38  #define TASK_SIZE_64           (UL(1) << vabits_user)
  39
  40  #ifdef CONFIG_COMPAT
  41 +#ifdef CONFIG_ARM64_64K_PAGES
  42 +/*
  43 + * With CONFIG_ARM64_64K_PAGES enabled, the last page is occupied
  44 + * by the compat vectors page.
  45 + */
  46  #define TASK_SIZE_32           UL(0x100000000)
  47 +#else
  48 +#define TASK_SIZE_32           (UL(0x100000000) - PAGE_SIZE)
  49 +#endif /* CONFIG_ARM64_64K_PAGES */
  50  #define TASK_SIZE              (test_thread_flag(TIF_32BIT) ? \
  51                                 TASK_SIZE_32 : TASK_SIZE_64)
  52  #define TASK_SIZE_OF(tsk)      (test_tsk_thread_flag(tsk, TIF_32BIT) ? \