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authorBrandon Phiilps <bphilips@suse.de>2010-02-10 01:20:06 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2010-03-15 08:50:06 -0700
commit0a660e1ef186efc73d7398b0a9ddba754adce5d2 (patch)
treeaab06fdc1778f8b65fc5992bb6815fce81e1661f /arch
parent81a1448f6f77f2fbbc4b9be64167533d2e2181cf (diff)
downloadlinux-linaro-stable-0a660e1ef186efc73d7398b0a9ddba754adce5d2.tar.gz
x86: Avoid race condition in pci_enable_msix()
commit ced5b697a76d325e7a7ac7d382dbbb632c765093 upstream. 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> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/apic/io_apic.c18
1 files changed, 5 insertions, 13 deletions
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index c107e837ed7d..e9a2f341b07c 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -3165,12 +3165,9 @@ unsigned int create_irq_nr(unsigned int irq_want, int node)
}
spin_unlock_irqrestore(&vector_lock, flags);
- if (irq > 0) {
- dynamic_irq_init(irq);
- /* restore it, in case dynamic_irq_init clear it */
- if (desc_new)
- desc_new->chip_data = cfg_new;
- }
+ if (irq > 0)
+ dynamic_irq_init_keep_chip_data(irq);
+
return irq;
}
@@ -3193,17 +3190,12 @@ void destroy_irq(unsigned int irq)
{
unsigned long flags;
struct irq_cfg *cfg;
- struct irq_desc *desc;
- /* store it, in case dynamic_irq_cleanup clear it */
- desc = irq_to_desc(irq);
- cfg = desc->chip_data;
- dynamic_irq_cleanup(irq);
- /* connect back irq_cfg */
- desc->chip_data = cfg;
+ dynamic_irq_cleanup_keep_chip_data(irq);
free_irte(irq);
spin_lock_irqsave(&vector_lock, flags);
+ cfg = irq_to_desc(irq)->chip_data;
__clear_irq_vector(irq, cfg);
spin_unlock_irqrestore(&vector_lock, flags);
}