x86: Avoid race condition in pci_enable_msix()
Keep chip_data in create_irq_nr and destroy_irq. When two drivers are setting up MSI-X at the same time via pci_enable_msix() there is a race. See this dmesg excerpt: [ 85.170610] ixgbe 0000:02:00.1: irq 97 for MSI/MSI-X [ 85.170611] alloc irq_desc for 99 on node -1 [ 85.170613] igb 0000:08:00.1: irq 98 for MSI/MSI-X [ 85.170614] alloc kstat_irqs on node -1 [ 85.170616] alloc irq_2_iommu on node -1 [ 85.170617] alloc irq_desc for 100 on node -1 [ 85.170619] alloc kstat_irqs on node -1 [ 85.170621] alloc irq_2_iommu on node -1 [ 85.170625] ixgbe 0000:02:00.1: irq 99 for MSI/MSI-X [ 85.170626] alloc irq_desc for 101 on node -1 [ 85.170628] igb 0000:08:00.1: irq 100 for MSI/MSI-X [ 85.170630] alloc kstat_irqs on node -1 [ 85.170631] alloc irq_2_iommu on node -1 [ 85.170635] alloc irq_desc for 102 on node -1 [ 85.170636] alloc kstat_irqs on node -1 [ 85.170639] alloc irq_2_iommu on node -1 [ 85.170646] BUG: unable to handle kernel NULL pointer dereference at 0000000000000088 As you can see igb and ixgbe are both alternating on create_irq_nr() via pci_enable_msix() in their probe function. ixgbe: While looping through irq_desc_ptrs[] via create_irq_nr() ixgbe choses irq_desc_ptrs[102] and exits the loop, drops vector_lock and calls dynamic_irq_init. Then it sets irq_desc_ptrs[102]->chip_data = NULL via dynamic_irq_init(). igb: Grabs the vector_lock now and starts looping over irq_desc_ptrs[] via create_irq_nr(). It gets to irq_desc_ptrs[102] and does this: cfg_new = irq_desc_ptrs[102]->chip_data; if (cfg_new->vector != 0) continue; This hits the NULL deref. Another possible race exists via pci_disable_msix() in a driver or in the number of error paths that call free_msi_irqs(): destroy_irq() dynamic_irq_cleanup() which sets desc->chip_data = NULL ...race window... desc->chip_data = cfg; Remove the save and restore code for cfg in create_irq_nr() and destroy_irq() and take the desc->lock when checking the irq_cfg. Reported-and-analyzed-by: Brandon Philips <bphilips@suse.de> Signed-off-by: Yinghai Lu <yinghai@kernel.org> LKML-Reference: <1265793639-15071-3-git-send-email-yinghai@kernel.org> Signed-off-by: Brandon Phililps <bphilips@suse.de> Cc: stable@kernel.org Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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@ -3228,12 +3228,9 @@ unsigned int create_irq_nr(unsigned int irq_want, int node)
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}
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spin_unlock_irqrestore(&vector_lock, flags);
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if (irq > 0) {
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dynamic_irq_init(irq);
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/* restore it, in case dynamic_irq_init clear it */
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if (desc_new)
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desc_new->chip_data = cfg_new;
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}
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if (irq > 0)
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dynamic_irq_init_keep_chip_data(irq);
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return irq;
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}
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@ -3256,17 +3253,12 @@ void destroy_irq(unsigned int irq)
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{
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unsigned long flags;
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struct irq_cfg *cfg;
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struct irq_desc *desc;
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/* store it, in case dynamic_irq_cleanup clear it */
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desc = irq_to_desc(irq);
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cfg = desc->chip_data;
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dynamic_irq_cleanup(irq);
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/* connect back irq_cfg */
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desc->chip_data = cfg;
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dynamic_irq_cleanup_keep_chip_data(irq);
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free_irte(irq);
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spin_lock_irqsave(&vector_lock, flags);
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cfg = irq_to_desc(irq)->chip_data;
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__clear_irq_vector(irq, cfg);
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spin_unlock_irqrestore(&vector_lock, flags);
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}
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@ -400,7 +400,9 @@ static inline int irq_has_action(unsigned int irq)
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/* Dynamic irq helper functions */
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extern void dynamic_irq_init(unsigned int irq);
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void dynamic_irq_init_keep_chip_data(unsigned int irq);
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extern void dynamic_irq_cleanup(unsigned int irq);
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void dynamic_irq_cleanup_keep_chip_data(unsigned int irq);
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/* Set/get chip/data for an IRQ: */
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extern int set_irq_chip(unsigned int irq, struct irq_chip *chip);
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@ -18,11 +18,7 @@
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#include "internals.h"
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/**
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* dynamic_irq_init - initialize a dynamically allocated irq
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* @irq: irq number to initialize
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*/
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void dynamic_irq_init(unsigned int irq)
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static void dynamic_irq_init_x(unsigned int irq, bool keep_chip_data)
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{
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struct irq_desc *desc;
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unsigned long flags;
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@ -41,7 +37,8 @@ void dynamic_irq_init(unsigned int irq)
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desc->depth = 1;
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desc->msi_desc = NULL;
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desc->handler_data = NULL;
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desc->chip_data = NULL;
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if (!keep_chip_data)
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desc->chip_data = NULL;
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desc->action = NULL;
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desc->irq_count = 0;
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desc->irqs_unhandled = 0;
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@ -55,10 +52,26 @@ void dynamic_irq_init(unsigned int irq)
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}
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/**
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* dynamic_irq_cleanup - cleanup a dynamically allocated irq
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* dynamic_irq_init - initialize a dynamically allocated irq
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* @irq: irq number to initialize
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*/
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void dynamic_irq_cleanup(unsigned int irq)
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void dynamic_irq_init(unsigned int irq)
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{
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dynamic_irq_init_x(irq, false);
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}
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/**
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* dynamic_irq_init_keep_chip_data - initialize a dynamically allocated irq
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* @irq: irq number to initialize
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*
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* does not set irq_to_desc(irq)->chip_data to NULL
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*/
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void dynamic_irq_init_keep_chip_data(unsigned int irq)
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{
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dynamic_irq_init_x(irq, true);
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}
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static void dynamic_irq_cleanup_x(unsigned int irq, bool keep_chip_data)
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{
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struct irq_desc *desc = irq_to_desc(irq);
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unsigned long flags;
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@ -77,7 +90,8 @@ void dynamic_irq_cleanup(unsigned int irq)
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}
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desc->msi_desc = NULL;
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desc->handler_data = NULL;
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desc->chip_data = NULL;
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if (!keep_chip_data)
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desc->chip_data = NULL;
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desc->handle_irq = handle_bad_irq;
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desc->chip = &no_irq_chip;
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desc->name = NULL;
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@ -85,6 +99,26 @@ void dynamic_irq_cleanup(unsigned int irq)
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raw_spin_unlock_irqrestore(&desc->lock, flags);
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}
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/**
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* dynamic_irq_cleanup - cleanup a dynamically allocated irq
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* @irq: irq number to initialize
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*/
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void dynamic_irq_cleanup(unsigned int irq)
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{
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dynamic_irq_cleanup_x(irq, false);
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}
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/**
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* dynamic_irq_cleanup_keep_chip_data - cleanup a dynamically allocated irq
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* @irq: irq number to initialize
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*
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* does not set irq_to_desc(irq)->chip_data to NULL
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*/
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void dynamic_irq_cleanup_keep_chip_data(unsigned int irq)
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{
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dynamic_irq_cleanup_x(irq, true);
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}
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/**
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* set_irq_chip - set the irq chip for an irq
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