From 3c6eeea358b4523a4590acf56be0b3f8d802ed68 Mon Sep 17 00:00:00 2001 From: Dietmar Maurer Date: Tue, 13 May 2014 07:06:49 +0200 Subject: [PATCH] add fix for CVE-2014-0196 --- Makefile | 3 +- changelog.Debian | 6 ++ ...write-crash-when-echoing-in-raw-mode.patch | 78 +++++++++++++++++++ 3 files changed, 86 insertions(+), 1 deletion(-) create mode 100644 n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch diff --git a/Makefile b/Makefile index fe10cff..ca4ecab 100644 --- a/Makefile +++ b/Makefile @@ -1,7 +1,7 @@ RELEASE=3.2 KERNEL_VER=3.10.0 -PKGREL=9 +PKGREL=10 # also include firmware of previous versrion into # the fw package: fwlist-2.6.32-PREV-pve KREL=2 @@ -147,6 +147,7 @@ ${KERNEL_SRC}/README: ${KERNEL_SRC}.org/README #cd ${KERNEL_SRC}; patch -p1 <../add-tiocgdev-ioctl.patch #cd ${KERNEL_SRC}; patch -p1 <../fix-nfs-block-count.patch #cd ${KERNEL_SRC}; patch -p1 <../fix-idr-header-for-drbd-compilation.patch + cd ${KERNEL_SRC}; patch -p1 <../n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch sed -i ${KERNEL_SRC}/Makefile -e 's/^EXTRAVERSION.*$$/EXTRAVERSION=${EXTRAVERSION}/' touch $@ diff --git a/changelog.Debian b/changelog.Debian index d38e10d..8346e4c 100644 --- a/changelog.Debian +++ b/changelog.Debian @@ -1,3 +1,9 @@ +pve-kernel-3.10.0 (3.10.0-10) unstable; urgency=low + + * add fix for CVE-2014-0196 + + -- Proxmox Support Team Tue, 13 May 2014 07:06:37 +0200 + pve-kernel-3.10.0 (3.10.0-9) unstable; urgency=low * enable BCACHE diff --git a/n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch b/n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch new file mode 100644 index 0000000..3d837a8 --- /dev/null +++ b/n_tty-Fix-n_tty_write-crash-when-echoing-in-raw-mode.patch @@ -0,0 +1,78 @@ +From: Peter Hurley + +commit 4291086b1f081b869c6d79e5b7441633dc3ace00 upstream. + +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 +Signed-off-by: Peter Hurley +Signed-off-by: Jiri Slaby +Cc: Linus Torvalds +Cc: Alan Cox +Signed-off-by: Greg Kroah-Hartman + +--- + drivers/tty/n_tty.c | 4 ++++ + 1 file changed, 4 insertions(+) + +--- a/drivers/tty/n_tty.c ++++ b/drivers/tty/n_tty.c +@@ -2066,8 +2066,12 @@ static ssize_t n_tty_write(struct tty_st + 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; + -- 2.39.2