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authorBrandon Phiilps <bphilips@suse.de>2010-02-10 01:20:06 -0800
committerH. Peter Anvin <hpa@zytor.com>2010-02-10 14:27:28 -0800
commitced5b697a76d325e7a7ac7d382dbbb632c765093 (patch)
tree1a0a56d4415afcd16d034aa3bc5c0a6ba06c8a52 /kernel/irq
parente28cab42f384745c8a947a9ccd51e4aae52f5d51 (diff)
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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>
Diffstat (limited to 'kernel/irq')
-rw-r--r--kernel/irq/chip.c52
1 files changed, 43 insertions, 9 deletions
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index ecc3fa2..d70394f 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -18,11 +18,7 @@
#include "internals.h"
-/**
- * dynamic_irq_init - initialize a dynamically allocated irq
- * @irq: irq number to initialize
- */
-void dynamic_irq_init(unsigned int irq)
+static void dynamic_irq_init_x(unsigned int irq, bool keep_chip_data)
{
struct irq_desc *desc;
unsigned long flags;
@@ -41,7 +37,8 @@ void dynamic_irq_init(unsigned int irq)
desc->depth = 1;
desc->msi_desc = NULL;
desc->handler_data = NULL;
- desc->chip_data = NULL;
+ if (!keep_chip_data)
+ desc->chip_data = NULL;
desc->action = NULL;
desc->irq_count = 0;
desc->irqs_unhandled = 0;
@@ -55,10 +52,26 @@ void dynamic_irq_init(unsigned int irq)
}
/**
- * dynamic_irq_cleanup - cleanup a dynamically allocated irq
+ * dynamic_irq_init - initialize a dynamically allocated irq
* @irq: irq number to initialize
*/
-void dynamic_irq_cleanup(unsigned int irq)
+void dynamic_irq_init(unsigned int irq)
+{
+ dynamic_irq_init_x(irq, false);
+}
+
+/**
+ * dynamic_irq_init_keep_chip_data - initialize a dynamically allocated irq
+ * @irq: irq number to initialize
+ *
+ * does not set irq_to_desc(irq)->chip_data to NULL
+ */
+void dynamic_irq_init_keep_chip_data(unsigned int irq)
+{
+ dynamic_irq_init_x(irq, true);
+}
+
+static void dynamic_irq_cleanup_x(unsigned int irq, bool keep_chip_data)
{
struct irq_desc *desc = irq_to_desc(irq);
unsigned long flags;
@@ -77,7 +90,8 @@ void dynamic_irq_cleanup(unsigned int irq)
}
desc->msi_desc = NULL;
desc->handler_data = NULL;
- desc->chip_data = NULL;
+ if (!keep_chip_data)
+ desc->chip_data = NULL;
desc->handle_irq = handle_bad_irq;
desc->chip = &no_irq_chip;
desc->name = NULL;
@@ -85,6 +99,26 @@ void dynamic_irq_cleanup(unsigned int irq)
raw_spin_unlock_irqrestore(&desc->lock, flags);
}
+/**
+ * dynamic_irq_cleanup - cleanup a dynamically allocated irq
+ * @irq: irq number to initialize
+ */
+void dynamic_irq_cleanup(unsigned int irq)
+{
+ dynamic_irq_cleanup_x(irq, false);
+}
+
+/**
+ * dynamic_irq_cleanup_keep_chip_data - cleanup a dynamically allocated irq
+ * @irq: irq number to initialize
+ *
+ * does not set irq_to_desc(irq)->chip_data to NULL
+ */
+void dynamic_irq_cleanup_keep_chip_data(unsigned int irq)
+{
+ dynamic_irq_cleanup_x(irq, true);
+}
+
/**
* set_irq_chip - set the irq chip for an irq