3.4-stable patches

added patches:
	n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch

diff --git a/queue-3.4/n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch b/queue-3.4/n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch
new file mode 100644 (file)
index 0000000..2b866f2
--- /dev/null
+++ b/queue-3.4/n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch
@@ -0,0 +1,77 @@
+From: Peter Hurley <peter@hurleysoftware.com>
+Date: Sat, 3 May 2014 14:04:59 +0200
+Subject: n_tty: Fix n_tty_write crash when echoing in raw mode
+
+commit 4291086b1f081b869c6d79e5b7441633dc3ace00 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
+d945cb9cce20ac7143c2de8d88b187f62db99bdc (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: Jiri Slaby <jslaby@suse.cz>
+Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
+Signed-off-by: Jiri Slaby <jslaby@suse.cz>
+Cc: Linus Torvalds <torvalds@linux-foundation.org>
+Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+[bwh: Backported to 3.2: output_lock is a member of struct tty_struct]
+Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
+---
+ drivers/tty/n_tty.c |    2 ++
+ 1 file changed, 2 insertions(+)
+
+--- a/drivers/tty/n_tty.c
++++ b/drivers/tty/n_tty.c
+@@ -1996,7 +1996,9 @@ static ssize_t n_tty_write(struct tty_st
+                               tty->ops->flush_chars(tty);
+               } else {
+                       while (nr > 0) {
++                              mutex_lock(&tty->output_lock);
+                               c = tty->ops->write(tty, b, nr);
++                              mutex_unlock(&tty->output_lock);
+                               if (c < 0) {
+                                       retval = c;
+                                       goto break_out;

diff --git a/queue-3.4/series b/queue-3.4/series
index 07f65a4e9b7d4435f4e5d7c3fc15fc7893742587..642b8048e7058bf8c0269d2d484f512db58a2c90 100644 (file)
--- a/queue-3.4/series
+++ b/queue-3.4/series
@@ -1 +1,2 @@
 scsi-megaraid-missing-bounds-check-in-mimd_to_kioc.patch
+n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch