From: Helge Deller <deller@gmx.de>
Date: Fri, 8 Apr 2016 16:18:48 +0000 (+0200)
Subject: parisc: Fix kernel crash with reversed copy_from_user()
X-Git-Tag: v4.5.2~119
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1abe5c5fa89d2730a6f4d4b1aaa3f847e5adeaa7;p=thirdparty%2Fkernel%2Fstable.git

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@gmx.de>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c
index 553b09855cfd8..77e2262c97f64 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);
 	    }