From: Andy Lutomirski Date: Tue, 26 Apr 2016 16:39:09 +0000 (-0700) Subject: x86/mm, sched/core: Turn off IRQs in switch_mm() X-Git-Tag: v4.1.12-124.31.3~1359 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=1421f7e7d87b12d9ff475431b0ac40d492e78250;p=users%2Fjedix%2Flinux-maple.git x86/mm, sched/core: Turn off IRQs in switch_mm() commit 078194f8e9fe3cf54c8fd8bded48a1db5bd8eb8a upstream. Potential races between switch_mm() and TLB-flush or LDT-flush IPIs could be very messy. AFAICT the code is currently okay, whether by accident or by careful design, but enabling PCID will make it considerably more complicated and will no longer be obviously safe. Fix it with a big hammer: run switch_mm() with IRQs off. To avoid a performance hit in the scheduler, we take advantage of our knowledge that the scheduler already has IRQs disabled when it calls switch_mm(). Signed-off-by: Andy Lutomirski Reviewed-by: Borislav Petkov Cc: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/f19baf759693c9dcae64bbff76189db77cb13398.1461688545.git.luto@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 4ead44fd2525ed97e5362a806d312a0e3b0ea445) Orabug: 27333760 CVE: CVE-2017-5754 Signed-off-by: Pavel Tatashin Conflicts: arch/x86/include/asm/mmu_context.h Signed-off-by: Kirtikar Kashyap --- diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index 83ca84004da8..1d07ebcc56ce 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -97,6 +97,10 @@ static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) extern void switch_mm(struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk); +extern void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, + struct task_struct *tsk); +#define switch_mm_irqs_off switch_mm_irqs_off + #define activate_mm(prev, next) \ do { \ paravirt_activate_mm((prev), (next)); \ diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 37b67a7c4218..fe5c7a8698bd 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -63,6 +63,16 @@ EXPORT_SYMBOL_GPL(leave_mm); void switch_mm(struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk) +{ + unsigned long flags; + + local_irq_save(flags); + switch_mm_irqs_off(prev, next, tsk); + local_irq_restore(flags); +} + +void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, + struct task_struct *tsk) { unsigned cpu = smp_processor_id();