tty: mark Siemens R3964 line discipline as BROKEN (CVE-2019-11486)

debian/changelog

@@ -832,6 +832,7 @@ linux (4.19.34-1) UNRELEASED; urgency=medium
   * inotify: Fix fsnotify_mark refcount leak in
     inotify_update_existing_watch() (CVE-2019-9857)
   * [x86] Disable R3964 due to lack of security support
+  * tty: mark Siemens R3964 line discipline as BROKEN (CVE-2019-11486)
 
   [ Aurelien Jarno ]
   * [mips] Fix indirect syscall tracing & seccomp filtering for big endian

debian/patches/bugfix/all/tty-mark-Siemens-R3964-line-discipline-as-BROKEN.patch

@@ -0,0 +1,46 @@
+From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Date: Fri, 5 Apr 2019 15:39:26 +0200
+Subject: tty: mark Siemens R3964 line discipline as BROKEN
+Origin: https://git.kernel.org/linus/c7084edc3f6d67750f50d4183134c4fb5712a5c8
+Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2019-11486
+
+The n_r3964 line discipline driver was written in a different time, when
+SMP machines were rare, and users were trusted to do the right thing.
+Since then, the world has moved on but not this code, it has stayed
+rooted in the past with its lovely hand-crafted list structures and
+loads of "interesting" race conditions all over the place.
+
+After attempting to clean up most of the issues, I just gave up and am
+now marking the driver as BROKEN so that hopefully someone who has this
+hardware will show up out of the woodwork (I know you are out there!)
+and will help with debugging a raft of changes that I had laying around
+for the code, but was too afraid to commit as odds are they would break
+things.
+
+Many thanks to Jann and Linus for pointing out the initial problems in
+this codebase, as well as many reviews of my attempts to fix the issues.
+It was a case of whack-a-mole, and as you can see, the mole won.
+
+Reported-by: Jann Horn <jannh@google.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+---
+ drivers/char/Kconfig | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
+index 72866a004f07..466ebd84ad17 100644
+--- a/drivers/char/Kconfig
++++ b/drivers/char/Kconfig
+@@ -348,7 +348,7 @@ config XILINX_HWICAP
+ 
+ config R3964
+ 	tristate "Siemens R3964 line discipline"
+-	depends on TTY
++	depends on TTY && BROKEN
+ 	---help---
+ 	  This driver allows synchronous communication with devices using the
+ 	  Siemens R3964 packet protocol. Unless you are dealing with special
+-- 
+2.11.0
+

debian/patches/series

@@ -149,6 +149,7 @@ debian/i386-686-pae-pci-set-pci-nobios-by-default.patch
 bugfix/all/xen-pciback-Don-t-disable-PCI_COMMAND-on-PCI-device-.patch
 debian/ntfs-mark-it-as-broken.patch
 bugfix/all/inotify-Fix-fsnotify_mark-refcount-leak-in-inotify_u.patch
+bugfix/all/tty-mark-Siemens-R3964-line-discipline-as-BROKEN.patch
 
 # Fix exported symbol versions
 bugfix/all/module-disable-matching-missing-version-crc.patch