linux-libre-lts-knock-3.10.39-2: fix CVE-2014-0196

2 files changed, 90 insertions, 3 deletions

diff --git a/kernels/linux-libre-lts-knock/0001-n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch b/kernels/linux-libre-lts-knock/0001-n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch
new file mode 100644
index 000000000..cb659dc7d
--- /dev/null
+++ b/kernels/linux-libre-lts-knock/0001-n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch
@@ -0,0 +1,83 @@
+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: [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@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>
+---
+ 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
+
diff --git a/kernels/linux-libre-lts-knock/PKGBUILD b/kernels/linux-libre-lts-knock/PKGBUILD
index 221f808eb..dab0fd29f 100644
--- a/kernels/linux-libre-lts-knock/PKGBUILD
+++ b/kernels/linux-libre-lts-knock/PKGBUILD
@@ -1,4 +1,4 @@
-# $Id: PKGBUILD 212087 2014-05-06 15:55:48Z bpiotrowski $
+# $Id: PKGBUILD 212332 2014-05-13 08:23:48Z bpiotrowski $
 # Maintainer: Tobias Powalowski <tpowa@archlinux.org>
 # Maintainer: Thomas Baechler <thomas@archlinux.org>
 # Maintainer (Parabola): André Silva <emulatorman@parabola.nu>
@@ -13,8 +13,8 @@ _basekernel=3.10
 _sublevel=39
 _knockpatchver=${_basekernel}
 pkgver=${_basekernel}.${_sublevel}
-pkgrel=1
-_lxopkgver=${_basekernel}.38 # nearly always the same as pkgver
+pkgrel=2
+_lxopkgver=${_basekernel}.39 # nearly always the same as pkgver
 arch=('i686' 'x86_64' 'mips64el')
 url="https://gnunet.org/knock"
 license=('GPL2')
@@ -32,6 +32,7 @@ source=("http://linux-libre.fsfla.org/pub/linux-libre/releases/${_basekernel}-gn
         'boot-logo.patch'
         'change-default-console-loglevel.patch'
         'criu-no-expert.patch'
+        '0001-n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch'
         "http://www.linux-libre.fsfla.org/pub/linux-libre/lemote/gnewsense/pool/debuginfo/linux-patches-${_lxopkgver}-gnu_0loongsonlibre_mipsel.tar.xz")
 md5sums=('d562fd52580a3b6b18b6eeb5921d1d5c'
          '0663686c1e5495b999a175aa7809ea92'
@@ -79,6 +80,9 @@ prepare() {
   # patch from fedora
   patch -Np1 -i "${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" == "mips64el" ]; then
     sed -i "s|^EXTRAVERSION.*|EXTRAVERSION =-libre-lts-knock|" Makefile
     sed -r "s|^( SUBLEVEL = ).*|\1$_sublevel|" \