From 8e1f74ea02cf4562404c48c6882214821552c13f Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 7 Sep 2016 09:54:34 -0700 Subject: usercopy: remove page-spanning test for now A custom allocator without __GFP_COMP that copies to userspace has been found in vmw_execbuf_process[1], so this disables the page-span checker by placing it behind a CONFIG for future work where such things can be tracked down later. [1] https://bugzilla.redhat.com/show_bug.cgi?id=1373326 Reported-by: Vinson Lee Fixes: f5509cc18daa ("mm: Hardened usercopy") Signed-off-by: Kees Cook --- security/Kconfig | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'security') diff --git a/security/Kconfig b/security/Kconfig index da10d9b..2dfc0ce 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -147,6 +147,17 @@ config HARDENED_USERCOPY or are part of the kernel text. This kills entire classes of heap overflow exploits and similar kernel memory exposures. +config HARDENED_USERCOPY_PAGESPAN + bool "Refuse to copy allocations that span multiple pages" + depends on HARDENED_USERCOPY + depends on !COMPILE_TEST + help + When a multi-page allocation is done without __GFP_COMP, + hardened usercopy will reject attempts to copy it. There are, + however, several cases of this in the kernel that have not all + been removed. This config is intended to be used only while + trying to find such users. + source security/selinux/Kconfig source security/smack/Kconfig source security/tomoyo/Kconfig -- cgit v1.1