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Emergency stacks have their thread_info mostly uninitialised, which in particular means garbage preempt_count values. Emergency stack code runs with interrupts disabled entirely, and is used very rarely, so this has been unnoticed so far. It was found by a proposed new powerpc watchdog that takes a soft-NMI directly from the masked_interrupt handler and using the emergency stack. That crashed at BUG_ON(in_nmi()) in nmi_enter(). preempt_count()s were found to be garbage. To fix this, zero the entire THREAD_SIZE allocation, and initialize the thread_info. Cc: stable@vger.kernel.org Reported-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Move it all into setup_64.c, use a function not a macro. Fix crashes on Cell by setting preempt_count to 0 not HARDIRQ_OFFSET] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> |
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| crypto | ||
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| kvm | ||
| lib | ||
| math-emu | ||
| mm | ||
| net | ||
| oprofile | ||
| perf | ||
| platforms | ||
| purgatory | ||
| sysdev | ||
| tools | ||
| xmon | ||
| Kconfig | ||
| Kconfig.debug | ||
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