[arch-commits] Commit in linux-lts/trunk (2 files)

[Bartłomiej Piotrowski]

    Date: Tuesday, May 13, 2014 @ 10:23:48
  Author: bpiotrowski
Revision: 212332

upgpkg: linux-lts 3.10.39-2

fix CVE-2014-0196

Added:
  linux-lts/trunk/0001-n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch
Modified:
  linux-lts/trunk/PKGBUILD

-----------------------------------------------------------------+
 0001-n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch |   83 ++++++++++
 PKGBUILD                                                        |   11 -
 2 files changed, 91 insertions(+), 3 deletions(-)

Added: 0001-n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch
===================================================================
--- 0001-n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch	                        (rev 0)
+++ 0001-n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch	2014-05-13 08:23:48 UTC (rev 212332)
@@ -0,0 +1,83 @@
+From 4291086b1f081b869c6d79e5b7441633dc3ace00 Mon Sep 17 00:00:00 2001
+From: Peter Hurley <peter at hurleysoftware.com>
+Date: Sat, 3 May 2014 14:04:59 +0200
+Subject: [PATCH] n_tty: Fix n_tty_write crash when echoing in raw mode
+
+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 at suse.cz>
+Signed-off-by: Peter Hurley <peter at hurleysoftware.com>
+Signed-off-by: Jiri Slaby <jslaby at suse.cz>
+Cc: Linus Torvalds <torvalds at linux-foundation.org>
+Cc: Alan Cox <alan at lxorguk.ukuu.org.uk>
+Cc: <stable at vger.kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
+---
+ drivers/tty/n_tty.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
+index 41fe8a0..fe9d129 100644
+--- a/drivers/tty/n_tty.c
++++ b/drivers/tty/n_tty.c
+@@ -2353,8 +2353,12 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
+ 			if (tty->ops->flush_chars)
+ 				tty->ops->flush_chars(tty);
+ 		} else {
++			struct n_tty_data *ldata = tty->disc_data;
++
+ 			while (nr > 0) {
++				mutex_lock(&ldata->output_lock);
+ 				c = tty->ops->write(tty, b, nr);
++				mutex_unlock(&ldata->output_lock);
+ 				if (c < 0) {
+ 					retval = c;
+ 					goto break_out;
+-- 
+1.9.2
+

Modified: PKGBUILD
===================================================================
--- PKGBUILD	2014-05-13 06:14:37 UTC (rev 212331)
+++ PKGBUILD	2014-05-13 08:23:48 UTC (rev 212332)
@@ -6,7 +6,7 @@
 #pkgbase=linux-custom       # Build kernel with a different name
 _srcname=linux-3.10
 pkgver=3.10.39
-pkgrel=1
+pkgrel=2
 arch=('i686' 'x86_64')
 url="http://www.kernel.org/"
 license=('GPL2')
@@ -19,7 +19,8 @@
         # standard config files for mkinitcpio ramdisk
         'linux-lts.preset'
         'change-default-console-loglevel.patch'
-        'criu-no-expert.patch')
+        'criu-no-expert.patch'
+        '0001-n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch')
 md5sums=('4f25cd5bec5f8d5a7d935b3f2ccb8481'
          'bfb4feed5a0c28bc0cb57b47bb6aed57'
          '45368ef5c1d03d375c31dcecabc5f0dd'
@@ -26,7 +27,8 @@
          'bf297cf1c74b06552b1013a09a27692f'
          '232b52576a62c7a333e9fe7a1e1ca359'
          'f3def2cefdcbb954c21d8505d23cc83c'
-         'd50c1ac47394e9aec637002ef3392bd1')
+         'd50c1ac47394e9aec637002ef3392bd1'
+         'da00b78faadbe939943b32305e4c68f8')
 
 _kernelname=${pkgbase#linux}
 
@@ -55,6 +57,9 @@
   # patch from fedora
   patch -Np1 -i "${srcdir}/criu-no-expert.patch"
 
+  # CVE-2014-0196
+  patch -Np1 -i "${srcdir}/0001-n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch"
+
   if [ "${CARCH}" = "x86_64" ]; then
     cat "${srcdir}/config.x86_64" > ./.config
   else