Patch "um: Fix kernel mode fault condition" has been added to the 4.2-stable tree

This is a note to let you know that I've just added the patch titled

um: Fix kernel mode fault condition

to the 4.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
um-fix-kernel-mode-fault-condition.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Richard Weinberger <[email protected]>
Date: Sun, 9 Aug 2015 22:26:33 +0200
Subject: um: Fix kernel mode fault condition

From: Richard Weinberger <[email protected]>

commit 56b88a3bf97a39d3f4f010509917b76a865a6dc8 upstream.

We have to exclude memory locations <= PAGE_SIZE from the condition and let the kernel mode fault path catch it. Otherwise a kernel NULL pointer exception will be reported as a kernel user space access.

---
 arch/um/kernel/trap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -220,7 +220,7 @@ unsigned long segv(struct faultinfo fi,
 		show_regs(container_of(regs, struct pt_regs, regs));
 		panic("Segfault with no mm");
 	}
-	else if (!is_user && address < TASK_SIZE) {
+	else if (!is_user && address > PAGE_SIZE && address < TASK_SIZE) {
 		show_regs(container_of(regs, struct pt_regs, regs));
 		panic("Kernel tried to access user memory at addr 0x%lx, ip 0x%lx",
 		       address, ip);

Patches currently in stable-queue which might be from [email protected] are

queue-4.2/um-fix-kernel-mode-fault-condition.patch