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    Subject[PATCHv4 0/5] Fix compatible mmap() return pointer over 4Gb
    Date
    Changes since v3:
    - fixed usage of 64-bit random mask for 32-bit mm->mmap_compat_base,
    during introducing mmap_compat{_legacy,}_base

    Changes since v2:
    - don't distinguish native and compat tasks by TIF_ADDR32,
    introduced mmap_compat{_legacy,}_base which allows to treat them
    the same
    - fixed kbuild errors

    Changes since v1:
    - Recalculate mmap_base instead of using max possible virtual address
    for compat/native syscall. That will make policy for allocation the
    same in 32-bit binaries and in 32-bit syscalls in 64-bit binaries.
    I need this because sys_mmap() in restored 32-bit process shouldn't
    hit the stack area.
    - Fixed mmap() with MAP_32BIT flag in the same usecases
    - used in_compat_syscall() helper rather TS_COMPAT check (Andy noticed)
    - introduced find_top() helper as suggested by Andy to simplify code
    - fixed test error-handeling: it checked the result of sys_mmap() with
    MMAP_FAILED, which is not correct, as it calls raw syscall - now
    checks return value to be aligned to PAGE_SIZE.

    Description from v1 [2]:

    A fix for bug in mmap() that I referenced in [1].
    Also selftest for it.

    I would like to mark the fix as for stable v4.9 kernel if it'll
    be accepted, as I try to support compatible 32-bit C/R
    after v4.9 and working compatible mmap() is really wanted there.

    [1]: https://marc.info/?l=linux-kernel&m=148311451525315
    [2]: https://marc.info/?l=linux-kernel&m=148415888707662

    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Borislav Petkov <bp@suse.de>
    Cc: x86@kernel.org
    Cc: linux-mm@kvack.org

    Dmitry Safonov (5):
    x86/mm: split arch_mmap_rnd() on compat/native versions
    x86/mm: introduce mmap{,_legacy}_base
    x86/mm: fix 32-bit mmap() for 64-bit ELF
    x86/mm: check in_compat_syscall() instead TIF_ADDR32 for
    mmap(MAP_32BIT)
    selftests/x86: add test to check compat mmap() return addr

    arch/Kconfig | 7 +
    arch/x86/Kconfig | 1 +
    arch/x86/include/asm/elf.h | 4 +-
    arch/x86/include/asm/processor.h | 3 +-
    arch/x86/kernel/sys_x86_64.c | 32 +++-
    arch/x86/mm/mmap.c | 89 +++++++----
    include/linux/mm_types.h | 5 +
    tools/testing/selftests/x86/Makefile | 2 +-
    tools/testing/selftests/x86/test_compat_mmap.c | 208 +++++++++++++++++++++++++
    9 files changed, 311 insertions(+), 40 deletions(-)
    create mode 100644 tools/testing/selftests/x86/test_compat_mmap.c

    --
    2.11.0

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