arm64: entry: Apply BP hardening for suspicious interrupts from EL0
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>
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@ -828,6 +828,11 @@ el0_irq_naked:
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#endif
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ct_user_exit
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#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
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tbz x22, #55, 1f
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bl do_el0_irq_bp_hardening
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1:
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#endif
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irq_handler
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#ifdef CONFIG_TRACE_IRQFLAGS
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@ -708,6 +708,12 @@ asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
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arm64_notify_die("", regs, &info, esr);
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}
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asmlinkage void __exception do_el0_irq_bp_hardening(void)
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{
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/* PC has already been checked in entry.S */
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arm64_apply_bp_hardening();
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}
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asmlinkage void __exception do_el0_ia_bp_hardening(unsigned long addr,
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unsigned int esr,
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struct pt_regs *regs)
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