Commit-ID: 94777fc51b3ad85ff9f705ddf7cdd0eb3bbad5a6 Gitweb: http://git.kernel.org/tip/94777fc51b3ad85ff9f705ddf7cdd0eb3bbad5a6 Author: Dimitri Sivanich <sivanich@xxxxxxx> AuthorDate: Tue, 16 Oct 2012 07:50:21 -0500 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Wed, 24 Oct 2012 12:53:51 +0200 x86/irq/ioapic: Check for valid irq_cfg pointer in smp_irq_move_cleanup_interrupt Posting this patch to fix an issue concerning sparse irq's that I raised a while back. There was discussion about adding refcounting to sparse irqs (to fix other potential race conditions), but that does not appear to have been addressed yet. This covers the only issue of this type that I've encountered in this area. A NULL pointer dereference can occur in smp_irq_move_cleanup_interrupt() if we haven't yet setup the irq_cfg pointer in the irq_desc.irq_data.chip_data. In create_irq_nr() there is a window where we have set vector_irq in __assign_irq_vector(), but not yet called irq_set_chip_data() to set the irq_cfg pointer. Should an IRQ_MOVE_CLEANUP_VECTOR hit the cpu in question during this time, smp_irq_move_cleanup_interrupt() will attempt to process the aforementioned irq, but panic when accessing irq_cfg. Only continue processing the irq if irq_cfg is non-NULL. Signed-off-by: Dimitri Sivanich <sivanich@xxxxxxx> Cc: Suresh Siddha <suresh.b.siddha@xxxxxxxxx> Cc: Joerg Roedel <joerg.roedel@xxxxxxx> Cc: Yinghai Lu <yinghai@xxxxxxxxxx> Cc: Alexander Gordeev <agordeev@xxxxxxxxxx> Link: http://lkml.kernel.org/r/20121016125021.GA22935@xxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/kernel/apic/io_apic.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index c265593..1817fa9 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -2257,6 +2257,9 @@ asmlinkage void smp_irq_move_cleanup_interrupt(void) continue; cfg = irq_cfg(irq); + if (!cfg) + continue; + raw_spin_lock(&desc->lock); /* -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html