Date: Monday, May 12, 2014 @ 20:58:13 Author: tpowa Revision: 212325 upgpkg: linux 3.14.3-2
fix CVE-2014-0196 Added: linux/trunk/CVE-2014-0196.patch Modified: linux/trunk/PKGBUILD ---------------------+ CVE-2014-0196.patch | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++ PKGBUILD | 7 +++- 2 files changed, 86 insertions(+), 1 deletion(-) Added: CVE-2014-0196.patch =================================================================== --- CVE-2014-0196.patch (rev 0) +++ CVE-2014-0196.patch 2014-05-12 18:58:13 UTC (rev 212325) @@ -0,0 +1,80 @@ +From 4291086b1f081b869c6d79e5b7441633dc3ace00 Mon Sep 17 00:00:00 2001 +From: Peter Hurley <[email protected]> +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 <[email protected]> +Signed-off-by: Peter Hurley <[email protected]> +Signed-off-by: Jiri Slaby <[email protected]> +Cc: Linus Torvalds <[email protected]> +Cc: Alan Cox <[email protected]> +Cc: <[email protected]> +Signed-off-by: Greg Kroah-Hartman <[email protected]> + +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 + Modified: PKGBUILD =================================================================== --- PKGBUILD 2014-05-12 18:57:52 UTC (rev 212324) +++ PKGBUILD 2014-05-12 18:58:13 UTC (rev 212325) @@ -6,7 +6,7 @@ #pkgbase=linux-custom # Build kernel with a different name _srcname=linux-3.14 pkgver=3.14.3 -pkgrel=1 +pkgrel=2 arch=('i686' 'x86_64') url="http://www.kernel.org/"; license=('GPL2') @@ -14,6 +14,7 @@ options=('!strip') source=("https://www.kernel.org/pub/linux/kernel/v3.x/${_srcname}.tar.xz"; "https://www.kernel.org/pub/linux/kernel/v3.x/patch-${pkgver}.xz"; + 'CVE-2014-0196.patch' # the main kernel config files 'config' 'config.x86_64' # standard config files for mkinitcpio ramdisk @@ -34,6 +35,7 @@ ) sha256sums=('61558aa490855f42b6340d1a1596be47454909629327c49a5e4e10268065dffa' 'a26a25739c50d639174698ae498530205b55e5a2b11f8c33ab92a8581bc83fbd' + '56d6dc13617645184e2a14b2ee466ccba5241961953f4950aed7377bc34902d7' 'c01d212694eddcf694c55e0943bf3336b6e1ff41b90ac1cdc88b26789785ed45' '9a33feb450005a43bf9aa8fbb74b2e463c72ea17ad06bab3357f8a0a89088e85' 'f0d90e756f14533ee67afda280500511a62465b4f76adcc5effa95a40045179c' @@ -59,6 +61,9 @@ # add upstream patch patch -p1 -i "${srcdir}/patch-${pkgver}" + # 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
