Hi all,
This version of Sahara's arch_within_stack_frames() series replaces the
open-coded stack walker with a call to arm64's existing walker.
Patch 2 can be tested independently with this change[0].
lkdtm's use of unallocated stack regions is a separate problem, patch 3
tries to address this.
Sahara, it would be good to get your review of this!
I'm afraid I omitted your patch-3 as it stopped the lkdtm test from working,
I suspect its not tricking the compiler, but I haven't investigated.
Thanks,
James
[0] Change to lkdtm to generate accesses that overlap stack frames.
--------------%<--------------
diff --git a/drivers/misc/lkdtm_usercopy.c b/drivers/misc/lkdtm_usercopy.c
index 1dd611423d8b..fcbba3a14387 100644
--- a/drivers/misc/lkdtm_usercopy.c
+++ b/drivers/misc/lkdtm_usercopy.c
@@ -57,7 +57,8 @@ static noinline void do_usercopy_stack(bool to_user, bool bad_frame)
/* This is a pointer to outside our current stack frame. */
if (bad_frame) {
- bad_stack = do_usercopy_stack_callee((uintptr_t)&bad_stack);
+ bad_stack = __builtin_frame_address(0);
+ bad_stack -= sizeof(good_stack)/2;
} else {
/* Put start address just inside stack. */
bad_stack = task_stack_page(current) + THREAD_SIZE;
--------------%<--------------
James Morse (2):
arm64: Add arch_within_stack_frames() for hardened usercopy
arm64/uaccess: Add hardened usercopy check for bad stack accesses
Sahara (1):
usercopy: create enum stack_type
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/thread_info.h | 7 ++++-
arch/arm64/include/asm/uaccess.h | 20 +++++++++++++
arch/arm64/kernel/stacktrace.c | 54 ++++++++++++++++++++++++++++++++++--
arch/x86/include/asm/thread_info.h | 19 +++++++------
include/linux/thread_info.h | 13 +++++++--
mm/usercopy.c | 8 +-----
7 files changed, 99 insertions(+), 23 deletions(-)
--
2.10.1