From: Will Deacon <[email protected]>
commit 5dfc6ed27710 upstream.
Software-step and PC alignment fault exceptions have higher priority than
instruction abort exceptions, so apply the BP hardening hooks there too
if the user PC appears to reside in kernel space.
Reported-by: Dan Hettena <[email protected]>
Reviewed-by: Marc Zyngier <[email protected]>
Signed-off-by: Will Deacon <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>
Signed-off-by: Alex Shi <[email protected]>
Conflicts:
expand enable_da_f to 'msr daifclr, #(8 | 4 | 1)'
in arch/arm64/kernel/entry.S
---
arch/arm64/kernel/entry.S | 6 ++++--
arch/arm64/mm/fault.c | 9 +++++++++
2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index bdb0139..d50c2fe 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -584,8 +584,10 @@ el0_sp_pc:
* Stack or PC alignment exception handling
*/
mrs x26, far_el1
- // enable interrupts before calling the main handler
- enable_dbg_and_irq
+ msr daifclr, #(8 | 4 | 1)
+#ifdef CONFIG_TRACE_IRQFLAGS
+ bl trace_hardirqs_off
+#endif
ct_user_exit
mov x0, x26
mov x1, x25
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index c95b194..6120a14 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -617,6 +617,12 @@ asmlinkage void __exception do_sp_pc_abort(unsigned long addr,
struct siginfo info;
struct task_struct *tsk = current;
+ if (user_mode(regs)) {
+ if (instruction_pointer(regs) > TASK_SIZE)
+ arm64_apply_bp_hardening();
+ local_irq_enable();
+ }
+
if (show_unhandled_signals && unhandled_signal(tsk, SIGBUS))
pr_info_ratelimited("%s[%d]: %s exception: pc=%p sp=%p\n",
tsk->comm, task_pid_nr(tsk),
@@ -676,6 +682,9 @@ asmlinkage int __exception do_debug_exception(unsigned long addr,
if (interrupts_enabled(regs))
trace_hardirqs_off();
+ if (user_mode(regs) && instruction_pointer(regs) > TASK_SIZE)
+ arm64_apply_bp_hardening();
+
if (!inf->fn(addr, esr, regs)) {
rv = 1;
} else {
--
2.7.4