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arm64: entry: Apply BP hardening for suspicious interrupts from EL0

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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 <dhettena@nvidia.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Will Deacon 2018-02-02 17:31:40 +00:00 • committed by Catalin Marinas
parent 5dfc6ed277
commit 30d88c0e3a
2 changed files with 11 additions and 0 deletions
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5
arch/arm64/kernel/entry.S
View file

@ -828,6 +828,11 @@ 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

6
arch/arm64/mm/fault.c
View file

@ -708,6 +708,12 @@ 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)