1. 11 Jun, 2017 16 commits
  2. 09 Jun, 2017 1 commit
  3. 08 Jun, 2017 17 commits
  4. 22 May, 2017 3 commits
    • James Morris's avatar
    • Linus Torvalds's avatar
      Linux 4.12-rc2 · 08332893
      Linus Torvalds authored
      08332893
    • Linus Torvalds's avatar
      x86: fix 32-bit case of __get_user_asm_u64() · 33c9e972
      Linus Torvalds authored
      The code to fetch a 64-bit value from user space was entirely buggered,
      and has been since the code was merged in early 2016 in commit
      b2f68038 ("x86/mm/32: Add support for 64-bit __get_user() on 32-bit
      kernels").
      
      Happily the buggered routine is almost certainly entirely unused, since
      the normal way to access user space memory is just with the non-inlined
      "get_user()", and the inlined version didn't even historically exist.
      
      The normal "get_user()" case is handled by external hand-written asm in
      arch/x86/lib/getuser.S that doesn't have either of these issues.
      
      There were two independent bugs in __get_user_asm_u64():
      
       - it still did the STAC/CLAC user space access marking, even though
         that is now done by the wrapper macros, see commit 11f1a4b9
         ("x86: reorganize SMAP handling in user space accesses").
      
         This didn't result in a semantic error, it just means that the
         inlined optimized version was hugely less efficient than the
         allegedly slower standard version, since the CLAC/STAC overhead is
         quite high on modern Intel CPU's.
      
       - the double register %eax/%edx was marked as an output, but the %eax
         part of it was touched early in the asm, and could thus clobber other
         inputs to the asm that gcc didn't expect it to touch.
      
         In particular, that meant that the generated code could look like
         this:
      
              mov    (%eax),%eax
              mov    0x4(%eax),%edx
      
         where the load of %edx obviously was _supposed_ to be from the 32-bit
         word that followed the source of %eax, but because %eax was
         overwritten by the first instruction, the source of %edx was
         basically random garbage.
      
      The fixes are trivial: remove the extraneous STAC/CLAC entries, and mark
      the 64-bit output as early-clobber to let gcc know that no inputs should
      alias with the output register.
      
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Benjamin LaHaise <bcrl@kvack.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: stable@kernel.org   # v4.8+
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      33c9e972
  5. 21 May, 2017 3 commits
    • Linus Torvalds's avatar
      Clean up x86 unsafe_get/put_user() type handling · 334a023e
      Linus Torvalds authored
      Al noticed that unsafe_put_user() had type problems, and fixed them in
      commit a7cc722f ("fix unsafe_put_user()"), which made me look more
      at those functions.
      
      It turns out that unsafe_get_user() had a type issue too: it limited the
      largest size of the type it could handle to "unsigned long".  Which is
      fine with the current users, but doesn't match our existing normal
      get_user() semantics, which can also handle "u64" even when that does
      not fit in a long.
      
      While at it, also clean up the type cast in unsafe_put_user().  We
      actually want to just make it an assignment to the expected type of the
      pointer, because we actually do want warnings from types that don't
      convert silently.  And it makes the code more readable by not having
      that one very long and complex line.
      
      [ This patch might become stable material if we ever end up back-porting
        any new users of the unsafe uaccess code, but as things stand now this
        doesn't matter for any current existing uses. ]
      
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      334a023e
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs · f3926e4c
      Linus Torvalds authored
      Pull misc uaccess fixes from Al Viro:
       "Fix for unsafe_put_user() (no callers currently in mainline, but
        anyone starting to use it will step into that) + alpha osf_wait4()
        infoleak fix"
      
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
        osf_wait4(): fix infoleak
        fix unsafe_put_user()
      f3926e4c
    • Linus Torvalds's avatar
      Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 970c305a
      Linus Torvalds authored
      Pull scheduler fix from Thomas Gleixner:
       "A single scheduler fix:
      
        Prevent idle task from ever being preempted. That makes sure that
        synchronize_rcu_tasks() which is ignoring idle task does not pretend
        that no task is stuck in preempted state. If that happens and idle was
        preempted on a ftrace trampoline the machine crashes due to
        inconsistent state"
      
      * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        sched/core: Call __schedule() from do_idle() without enabling preemption
      970c305a