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 <stable@xxxxxxxxxxxxxxx> know about it.
>From 56b88a3bf97a39d3f4f010509917b76a865a6dc8 Mon Sep 17 00:00:00 2001
From: Richard Weinberger <richard@xxxxxx>
Date: Sun, 9 Aug 2015 22:26:33 +0200
Subject: um: Fix kernel mode fault condition
From: Richard Weinberger <richard@xxxxxx>
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.
Fixes: d2313084e2c (um: Catch unprotected user memory access)
Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/um/kernel/trap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -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 richard@xxxxxx are
queue-4.2/um-fix-kernel-mode-fault-condition.patch
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