1. 21 6月, 2009 1 次提交
    • L
      x86: don't use 'access_ok()' as a range check in get_user_pages_fast() · 7f818906
      Linus Torvalds 提交于
      It's really not right to use 'access_ok()', since that is meant for the
      normal "get_user()" and "copy_from/to_user()" accesses, which are done
      through the TLB, rather than through the page tables.
      
      Why? access_ok() does both too few, and too many checks.  Too many,
      because it is meant for regular kernel accesses that will not honor the
      'user' bit in the page tables, and because it honors the USER_DS vs
      KERNEL_DS distinction that we shouldn't care about in GUP.  And too few,
      because it doesn't do the 'canonical' check on the address on x86-64,
      since the TLB will do that for us.
      
      So instead of using a function that isn't meant for this, and does
      something else and much more complicated, just do the real rules: we
      don't want the range to overflow, and on x86-64, we want it to be a
      canonical low address (on 32-bit, all addresses are canonical).
      Acked-by: NIngo Molnar <mingo@elte.hu>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7f818906
  2. 20 6月, 2009 39 次提交