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SubjectRe: [PATCHv4 0/5] Fix compatible mmap() return pointer over 4Gb
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On 01/30/2017 03:04 PM, Dmitry Safonov wrote:
> 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.

Gentle ping. Any thought on this?

>
> [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
>


--
Dmitry

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