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 <pe...@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 <jsl...@suse.cz> +Signed-off-by: Peter Hurley <pe...@hurleysoftware.com> +Signed-off-by: Jiri Slaby <jsl...@suse.cz> +Cc: Linus Torvalds <torva...@linux-foundation.org> +Cc: Alan Cox <a...@lxorguk.ukuu.org.uk> +Cc: <sta...@vger.kernel.org> +Signed-off-by: Greg Kroah-Hartman <gre...@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