• Kirill A. Shutemov's avatar
    x86/mpx: Do not set ->vm_ops on MPX VMAs · a8965276
    Kirill A. Shutemov authored
    MPX setups private anonymous mapping, but uses vma->vm_ops too.
    This can confuse core VM, as it relies on vm->vm_ops to
    distinguish file VMAs from anonymous.
    
    As result we will get SIGBUS, because handle_pte_fault() thinks
    it's file VMA without vm_ops->fault and it doesn't know how to
    handle the situation properly.
    
    Let's fix that by not setting ->vm_ops.
    
    We don't really need ->vm_ops here: MPX VMA can be detected with
    VM_MPX flag. And vma_merge() will not merge MPX VMA with non-MPX
    VMA, because ->vm_flags won't match.
    
    The only thing left is name of VMA. I'm not sure if it's part of
    ABI, or we can just drop it. The patch keep it by providing
    arch_vma_name() on x86.
    Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
    Cc: <stable@vger.kernel.org> # Fixes: 6b7339f4 (mm: avoid setting up anonymous pages into file mapping)
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: dave@sr71.net
    Link: http://lkml.kernel.org/r/20150720212958.305CC3E9@viggo.jf.intel.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    a8965276
mmap.c 3.32 KB