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>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c
index b3f87a3b4bcee589819b405b979f7a1c0c917472..0c329b2c5df405910a09ba20e59b7785285459fb 100644 (file)
--- a/arch/parisc/kernel/traps.c
+++ b/arch/parisc/kernel/traps.c
@@ -811,6 +811,9 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
 
            if (fault_space == 0 && !in_atomic())
            {
+               /* 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);
            }