From 34dc20b03d0e9361c86865adcb9ae7516339cfdb Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Thu, 12 Apr 2018 12:11:18 +0100 Subject: arm64: entry: Apply BP hardening for suspicious interrupts from EL0 From: Will Deacon commit 30d88c0e3ace625a92eead9ca0ad94093a8f59fe upstream. It is possible to take an IRQ from EL0 following a branch to a kernel address in such a way that the IRQ is prioritised over the instruction abort. Whilst an attacker would need to get the stars to align here, it might be sufficient with enough calibration so perform BP hardening in the rare case that we see a kernel address in the ELR when handling an IRQ from EL0. Reported-by: Dan Hettena Reviewed-by: Marc Zyngier Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Mark Rutland [v4.9 backport] Tested-by: Greg Hackmann Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/entry.S | 5 +++++ arch/arm64/mm/fault.c | 6 ++++++ 2 files changed, 11 insertions(+) (limited to 'arch/arm64') diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 30f4331d477a..b79e302d2a3e 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -686,6 +686,11 @@ el0_irq_naked: #endif ct_user_exit +#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR + tbz x22, #55, 1f + bl do_el0_irq_bp_hardening +1: +#endif irq_handler #ifdef CONFIG_TRACE_IRQFLAGS diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 6120a1486054..ad49ae8f3967 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -590,6 +590,12 @@ asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr, arm64_notify_die("", regs, &info, esr); } +asmlinkage void __exception do_el0_irq_bp_hardening(void) +{ + /* PC has already been checked in entry.S */ + arm64_apply_bp_hardening(); +} + asmlinkage void __exception do_el0_ia_bp_hardening(unsigned long addr, unsigned int esr, struct pt_regs *regs) -- cgit v1.2.3