diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2017-11-15 17:36:06 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2017-11-16 11:43:11 +0100 |
| commit | 1e0f25dbf2464df8445dd40881f4d9e732434947 (patch) | |
| tree | 2075553f47e8085b712c21f1c8b60b4e5bbcef00 /arch/x86/include | |
| parent | 6e2a3064d6a86094fecc20cd430fd96aaa801687 (diff) | |
x86/mm: Prevent non-MAP_FIXED mapping across DEFAULT_MAP_WINDOW border
In case of 5-level paging, the kernel does not place any mapping above
47-bit, unless userspace explicitly asks for it.
Userspace can request an allocation from the full address space by
specifying the mmap address hint above 47-bit.
Nicholas noticed that the current implementation violates this interface:
If user space requests a mapping at the end of the 47-bit address space
with a length which causes the mapping to cross the 47-bit border
(DEFAULT_MAP_WINDOW), then the vma is partially in the address space
below and above.
Sanity check the mmap address hint so that start and end of the resulting
vma are on the same side of the 47-bit border. If that's not the case fall
back to the code path which ignores the address hint and allocate from the
regular address space below 47-bit.
To make the checks consistent, mask out the address hints lower bits
(either PAGE_MASK or huge_page_mask()) instead of using ALIGN() which can
push them up to the next boundary.
[ tglx: Moved the address check to a function and massaged comment and
changelog ]
Reported-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/20171115143607.81541-1-kirill.shutemov@linux.intel.com
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/elf.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h index 3a091cea36c5..0d157d2a1e2a 100644 --- a/arch/x86/include/asm/elf.h +++ b/arch/x86/include/asm/elf.h @@ -309,6 +309,7 @@ static inline int mmap_is_ia32(void) extern unsigned long task_size_32bit(void); extern unsigned long task_size_64bit(int full_addr_space); extern unsigned long get_mmap_base(int is_legacy); +extern bool mmap_address_hint_valid(unsigned long addr, unsigned long len); #ifdef CONFIG_X86_32 |