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  1. 09 Jun, 2014 36 commits
  3. 18 May, 2014 4 commits
    • Ben Hutchings's avatar
      Linux 3.2.59 · 382ae9d0
      Ben Hutchings authored
      382ae9d0
    • Matthew Daley's avatar
      floppy: don't write kernel-only members to FDRAWCMD ioctl output · 629cbea2
      Matthew Daley authored 
      commit 2145e15e upstream.

Do not leak kernel-only floppy_raw_cmd structure members to userspace.
This includes the linked-list pointer and the pointer to the allocated
DMA space.
Signed-off-by: default avatarMatthew Daley <mattd@bugfuzz.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      629cbea2
    • Matthew Daley's avatar
      floppy: ignore kernel-only members in FDRAWCMD ioctl input · d79119d4
      Matthew Daley authored 
      commit ef87dbe7 upstream.

Always clear out these floppy_raw_cmd struct members after copying the
entire structure from userspace so that the in-kernel version is always
valid and never left in an interdeterminate state.
Signed-off-by: default avatarMatthew Daley <mattd@bugfuzz.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      d79119d4
    • Peter Hurley's avatar
      n_tty: Fix n_tty_write crash when echoing in raw mode · 1e509971
      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>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: output_lock is a member of struct tty_struct]
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      1e509971
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