[4.2.y-ckt stable] Patch "parisc: Fix kernel crash with reversed copy_from_user()" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    parisc: Fix kernel crash with reversed copy_from_user()

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt8.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 92d72797d7588424dde1d7d046eb0b7e03c35b2b Mon Sep 17 00:00:00 2001
From: Helge Deller <deller at gmx.de>
Date: Fri, 8 Apr 2016 18:18:48 +0200
Subject: parisc: Fix kernel crash with reversed copy_from_user()

commit ef72f3110d8b19f4c098a0bff7ed7d11945e70c6 upstream.

The kernel module testcase (lib/test_user_copy.c) exhibited a kernel
crash on parisc if the parameters for copy_from_user were reversed
("illegal reversed copy_to_user" testcase).

Fix this potential crash by checking the fault handler if the faulting
address is in the exception table.

Signed-off-by: Helge Deller <deller at gmx.de>
Cc: Kees Cook <keescook at chromium.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 arch/parisc/kernel/traps.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c
index b99b39f..3419668 100644
--- a/arch/parisc/kernel/traps.c
+++ b/arch/parisc/kernel/traps.c
@@ -798,6 +798,9 @@ void notrace handle_interruption(int code, struct pt_regs *regs)

 	    if (fault_space == 0 && !faulthandler_disabled())
 	    {
+		/* Clean up and return if in exception table. */
+		if (fixup_exception(regs))
+			return;
 		pdc_chassis_send_status(PDC_CHASSIS_DIRECT_PANIC);
 		parisc_terminate("Kernel Fault", regs, code, fault_address);
 	    }
--
2.7.4