From: Russell King <rmk+kernel@arm.linux.org.uk>
Date: Fri, 11 Sep 2015 18:18:28 +0000 (+0100)
Subject: Merge branch 'uaccess' into fixes
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=c2172ce2303051764829d4958bd50a11ada0590f;p=linux-beck.git

Merge branch 'uaccess' into fixes
---

c2172ce2303051764829d4958bd50a11ada0590f
diff --cc arch/arm/Kconfig
index 1c5021002fe4,e15d5ed4d5f1..a7a2e328edf9
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@@ -1693,13 -1693,22 +1693,28 @@@ config HIGHME
  config HIGHPTE
  	bool "Allocate 2nd-level pagetables from highmem"
  	depends on HIGHMEM
 +	help
 +	  The VM uses one page of physical memory for each page table.
 +	  For systems with a lot of processes, this can use a lot of
 +	  precious low memory, eventually leading to low memory being
 +	  consumed by page tables.  Setting this option will allow
 +	  user-space 2nd level page tables to reside in high memory.
  
+ config CPU_SW_DOMAIN_PAN
+ 	bool "Enable use of CPU domains to implement privileged no-access"
+ 	depends on MMU && !ARM_LPAE
+ 	default y
+ 	help
+ 	  Increase kernel security by ensuring that normal kernel accesses
+ 	  are unable to access userspace addresses.  This can help prevent
+ 	  use-after-free bugs becoming an exploitable privilege escalation
+ 	  by ensuring that magic values (such as LIST_POISON) will always
+ 	  fault when dereferenced.
+ 
+ 	  CPUs with low-vector mappings use a best-efforts implementation.
+ 	  Their lower 1MB needs to remain accessible for the vectors, but
+ 	  the remainder of userspace will become appropriately inaccessible.
+ 
  config HW_PERF_EVENTS
  	bool "Enable hardware performance counter support for perf events"
  	depends on PERF_EVENTS