The patch titled
Subject: kasan, arm64: fix up fault handling logic
has been added to the -mm tree. Its filename is
kasan-arm64-fix-up-fault-handling-logic.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kasan-arm64-fix-up-fault-handling-logic.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kasan-arm64-fix-up-fault-handling-logic.patch
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------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: kasan, arm64: fix up fault handling logic
Right now arm64 fault handling code removes pointer tags from addresses
covered by TTBR0 in faults taken from both EL0 and EL1, but doesn't do
that for pointers covered by TTBR1.
This patch adds two helper functions is_ttbr0_addr() and is_ttbr1_addr(),
where the latter one accounts for the fact that TTBR1 pointers might be
tagged when tag-based KASAN is in use, and uses these helper functions to
perform pointer checks in arch/arm64/mm/fault.c.
Link: http://lkml.kernel.org/r/a54fe8c8c11948b0ac8c8b285fb36f845217c84a.1543337629.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Suggested-by: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/arch/arm64/mm/fault.c~kasan-arm64-fix-up-fault-handling-logic
+++ a/arch/arm64/mm/fault.c
@@ -40,6 +40,7 @@
#include <asm/daifflags.h>
#include <asm/debug-monitors.h>
#include <asm/esr.h>
+#include <asm/kasan.h>
#include <asm/sysreg.h>
#include <asm/system_misc.h>
#include <asm/pgtable.h>
@@ -132,6 +133,18 @@ static void mem_abort_decode(unsigned in
data_abort_decode(esr);
}
+static inline bool is_ttbr0_addr(unsigned long addr)
+{
+ /* entry assembly clears tags for TTBR0 addrs */
+ return addr < TASK_SIZE;
+}
+
+static inline bool is_ttbr1_addr(unsigned long addr)
+{
+ /* TTBR1 addresses may have a tag if KASAN_SW_TAGS is in use */
+ return arch_kasan_reset_tag(addr) >= VA_START;
+}
+
/*
* Dump out the page tables associated with 'addr' in the currently active mm.
*/
@@ -141,7 +154,7 @@ void show_pte(unsigned long addr)
pgd_t *pgdp;
pgd_t pgd;
- if (addr < TASK_SIZE) {
+ if (is_ttbr0_addr(addr)) {
/* TTBR0 */
mm = current->active_mm;
if (mm == &init_mm) {
@@ -149,7 +162,7 @@ void show_pte(unsigned long addr)
addr);
return;
}
- } else if (addr >= VA_START) {
+ } else if (is_ttbr1_addr(addr)) {
/* TTBR1 */
mm = &init_mm;
} else {
@@ -254,7 +267,7 @@ static inline bool is_el1_permission_fau
if (fsc_type == ESR_ELx_FSC_PERM)
return true;
- if (addr < TASK_SIZE && system_uses_ttbr0_pan())
+ if (is_ttbr0_addr(addr) && system_uses_ttbr0_pan())
return fsc_type == ESR_ELx_FSC_FAULT &&
(regs->pstate & PSR_PAN_BIT);
@@ -319,7 +332,7 @@ static void set_thread_esr(unsigned long
* type", so we ignore this wrinkle and just return the translation
* fault.)
*/
- if (current->thread.fault_address >= TASK_SIZE) {
+ if (!is_ttbr0_addr(current->thread.fault_address)) {
switch (ESR_ELx_EC(esr)) {
case ESR_ELx_EC_DABT_LOW:
/*
@@ -455,7 +468,7 @@ static int __kprobes do_page_fault(unsig
mm_flags |= FAULT_FLAG_WRITE;
}
- if (addr < TASK_SIZE && is_el1_permission_fault(addr, esr, regs)) {
+ if (is_ttbr0_addr(addr) && is_el1_permission_fault(addr, esr, regs)) {
/* regs->orig_addr_limit may be 0 if we entered from EL0 */
if (regs->orig_addr_limit == KERNEL_DS)
die_kernel_fault("access to user memory with fs=KERNEL_DS",
@@ -603,7 +616,7 @@ static int __kprobes do_translation_faul
unsigned int esr,
struct pt_regs *regs)
{
- if (addr < TASK_SIZE)
+ if (is_ttbr0_addr(addr))
return do_page_fault(addr, esr, regs);
do_bad_area(addr, esr, regs);
@@ -758,7 +771,7 @@ asmlinkage void __exception do_el0_ia_bp
* re-enabled IRQs. If the address is a kernel address, apply
* BP hardening prior to enabling IRQs and pre-emption.
*/
- if (addr > TASK_SIZE)
+ if (!is_ttbr0_addr(addr))
arm64_apply_bp_hardening();
local_daif_restore(DAIF_PROCCTX);
@@ -771,7 +784,7 @@ asmlinkage void __exception do_sp_pc_abo
struct pt_regs *regs)
{
if (user_mode(regs)) {
- if (instruction_pointer(regs) > TASK_SIZE)
+ if (!is_ttbr0_addr(instruction_pointer(regs)))
arm64_apply_bp_hardening();
local_daif_restore(DAIF_PROCCTX);
}
@@ -825,7 +838,7 @@ asmlinkage int __exception do_debug_exce
if (interrupts_enabled(regs))
trace_hardirqs_off();
- if (user_mode(regs) && instruction_pointer(regs) > TASK_SIZE)
+ if (user_mode(regs) && !is_ttbr0_addr(instruction_pointer(regs)))
arm64_apply_bp_hardening();
if (!inf->fn(addr, esr, regs)) {
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are
kasan-mm-change-hooks-signatures.patch
kasan-slub-handle-pointer-tags-in-early_kmem_cache_node_alloc.patch
kasan-move-common-generic-and-tag-based-code-to-commonc.patch
kasan-rename-source-files-to-reflect-the-new-naming-scheme.patch
kasan-add-config_kasan_generic-and-config_kasan_sw_tags.patch
kasan-arm64-adjust-shadow-size-for-tag-based-mode.patch
kasan-rename-kasan_zero_page-to-kasan_early_shadow_page.patch
kasan-initialize-shadow-to-0xff-for-tag-based-mode.patch
arm64-move-untagged_addr-macro-from-uaccessh-to-memoryh.patch
kasan-add-tag-related-helper-functions.patch
kasan-arm64-untag-address-in-_virt_addr_is_linear.patch
kasan-preassign-tags-to-objects-with-ctors-or-slab_typesafe_by_rcu.patch
kasan-arm64-fix-up-fault-handling-logic.patch
kasan-arm64-enable-top-byte-ignore-for-the-kernel.patch
kasan-mm-perform-untagged-pointers-comparison-in-krealloc.patch
kasan-split-out-generic_reportc-from-reportc.patch
kasan-add-bug-reporting-routines-for-tag-based-mode.patch
mm-move-obj_to_index-to-include-linux-slab_defh.patch
kasan-add-hooks-implementation-for-tag-based-mode.patch
kasan-arm64-add-brk-handler-for-inline-instrumentation.patch
kasan-mm-arm64-tag-non-slab-memory-allocated-via-pagealloc.patch
kasan-add-__must_check-annotations-to-kasan-hooks.patch
kasan-arm64-select-have_arch_kasan_sw_tags.patch
kasan-update-documentation.patch
kasan-add-spdx-license-identifier-mark-to-source-files.patch
