1. 07 May, 2014 2 commits
    • Christian Borntraeger's avatar
      KVM: s390: Optimize ucontrol path · eb81abce
      Christian Borntraeger authored
      commit 2955c83f upstream.
      
      Since commit 7c470539
      (s390/kvm: avoid automatic sie reentry) we will run through the C code
      of KVM on host interrupts instead of just reentering the guest. This
      will result in additional ucontrol exits (at least HZ per second). Let
      handle a 0 intercept in the kernel and dont return to userspace,
      even if in ucontrol mode.
      Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      Reviewed-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
      [ luis: backported to 3.11: adjusted context ]
      Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
      eb81abce
    • Peter Hurley's avatar
      n_tty: Fix n_tty_write crash when echoing in raw mode · 64ec813a
      Peter Hurley authored
      commit 4291086b upstream.
      
      The tty atomic_write_lock does not provide an exclusion guarantee for
      the tty driver if the termios settings are LECHO & !OPOST.  And since
      it is unexpected and not allowed to call TTY buffer helpers like
      tty_insert_flip_string concurrently, this may lead to crashes when
      concurrect writers call pty_write. In that case the following two
      writers:
      * the ECHOing from a workqueue and
      * pty_write from the process
      race and can overflow the corresponding TTY buffer like follows.
      
      If we look into tty_insert_flip_string_fixed_flag, there is:
        int space = __tty_buffer_request_room(port, goal, flags);
        struct tty_buffer *tb = port->buf.tail;
        ...
        memcpy(char_buf_ptr(tb, tb->used), chars, space);
        ...
        tb->used += space;
      
      so the race of the two can result in something like this:
                    A                                B
      __tty_buffer_request_room
                                        __tty_buffer_request_room
      memcpy(buf(tb->used), ...)
      tb->used += space;
                                        memcpy(buf(tb->used), ...) ->BOOM
      
      B's memcpy is past the tty_buffer due to the previous A's tb->used
      increment.
      
      Since the N_TTY line discipline input processing can output
      concurrently with a tty write, obtain the N_TTY ldisc output_lock to
      serialize echo output with normal tty writes.  This ensures the tty
      buffer helper tty_insert_flip_string is not called concurrently and
      everything is fine.
      
      Note that this is nicely reproducible by an ordinary user using
      forkpty and some setup around that (raw termios + ECHO). And it is
      present in kernels at least after commit
      d945cb9c (pty: Rework the pty layer to
      use the normal buffering logic) in 2.6.31-rc3.
      
      js: add more info to the commit log
      js: switch to bool
      js: lock unconditionally
      js: lock only the tty->ops->write call
      
      References: CVE-2014-0196
      Reported-and-tested-by: default avatarJiri Slaby <jslaby@suse.cz>
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
      64ec813a
  2. 06 May, 2014 3 commits
  3. 05 May, 2014 22 commits
  4. 02 May, 2014 3 commits
  5. 30 Apr, 2014 3 commits
  6. 29 Apr, 2014 7 commits