linux-libre-{pae,xen}-3.14.3-2: fix CVE-2014-0196

2 files changed, 87 insertions, 2 deletions

diff --git a/kernels/linux-libre-xen/CVE-2014-0196.patch b/kernels/linux-libre-xen/CVE-2014-0196.patch
new file mode 100644
index 000000000..a58707d56
--- /dev/null
+++ b/kernels/linux-libre-xen/CVE-2014-0196.patch
@@ -0,0 +1,80 @@
+From 4291086b1f081b869c6d79e5b7441633dc3ace00 Mon Sep 17 00:00:00 2001
+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
+
+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>
+Cc: <stable@vger.kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+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;
+-- 
+cgit v0.10.1-7-g08dc
+
diff --git a/kernels/linux-libre-xen/PKGBUILD b/kernels/linux-libre-xen/PKGBUILD
index 3bfe1dc4a..5b551e90f 100644
--- a/kernels/linux-libre-xen/PKGBUILD
+++ b/kernels/linux-libre-xen/PKGBUILD
@@ -1,4 +1,4 @@
-# $Id: PKGBUILD 212093 2014-05-06 20:49:41Z tpowa $
+# $Id: PKGBUILD 212325 2014-05-12 18:58:13Z tpowa $
 # Contributor: Tobias Powalowski <tpowa@archlinux.org>
 # Contributor: Thomas Baechler <thomas@archlinux.org>
 # Maintainer (Parabola): André Silva <emulatorman@parabola.nu>
@@ -7,7 +7,7 @@ pkgbase=linux-libre-xen     # Build stock -LIBRE-XEN kernel
 #pkgbase=linux-libre-custom # Build kernel with a different name
 _basekernel=3.14
 pkgver=${_basekernel}.3
-pkgrel=1
+pkgrel=2
 arch=('i686')
 url="http://linux-libre.fsfla.org/"
 license=('GPL2')
@@ -15,6 +15,7 @@ makedepends=('xmlto' 'docbook-xsl' 'kmod' 'inetutils' 'bc')
 options=('!strip')
 source=("http://linux-libre.fsfla.org/pub/linux-libre/releases/${_basekernel}-gnu/linux-libre-${_basekernel}-gnu.tar.xz"
         "http://linux-libre.fsfla.org/pub/linux-libre/releases/${pkgver}-gnu/patch-${_basekernel}-gnu-${pkgver}-gnu.xz"
+        'CVE-2014-0196.patch'
         # the main kernel config files
         'config'
         # standard config files for mkinitcpio ramdisk
@@ -34,6 +35,7 @@ source=("http://linux-libre.fsfla.org/pub/linux-libre/releases/${_basekernel}-gn
         '0015-fix-xsdt-validation.patch')
 sha256sums=('477555c709b9407fe37dbd70d3331ff9dde1f9d874aba2741f138d07ae6f281b'
             'fcd8398a41a7e55e44123857342fd9041ae1bdacbcf8c5099a53293c96e6fba6'
+            '56d6dc13617645184e2a14b2ee466ccba5241961953f4950aed7377bc34902d7'
             '44d0749d9d2d7f8eec93b260ab5d601433c43d8bf16b6685c3811cf43ba0ed91'
             '7a475ada892857397cf80d2de777825ae94758dc2d9dfa3754ae3d670f4a2f02'
             '8303b426b1a6dce456b2350003558ae312d21cab0ae6c1f0d7b9d21395f4e177'
@@ -63,6 +65,9 @@ prepare() {
   # add freedo as boot logo
   patch -p1 -i "${srcdir}/boot-logo.patch"
 
+  # fix upstream CVE-2014-0196
+  patch -p1 -i "${srcdir}/CVE-2014-0196.patch"
+
   # add latest fixes from stable queue, if needed
   # http://git.kernel.org/?p=linux/kernel/git/stable/stable-queue.git