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authorGreg Edwards <gedwards@ddn.com>2014-07-23 10:13:26 -0600
committerJoerg Roedel <jroedel@suse.de>2014-07-31 13:45:05 +0200
commitaf437469d14e91e8b4273606cac4c08f05bf056e (patch)
tree303694d6ef5d040a1e683c9319f347c5bee4b2e0 /drivers/iommu/intel_irq_remapping.c
parentc875d2c1b8083cd627ea0463e20bf22c2d7421ee (diff)
downloadop-kernel-dev-af437469d14e91e8b4273606cac4c08f05bf056e.zip
op-kernel-dev-af437469d14e91e8b4273606cac4c08f05bf056e.tar.gz
iommu/vt-d: Fix race setting IRQ CPU affinity while freeing IRQ
A user process setting the CPU affinity of an IRQ for a KVM direct-assigned device via /proc/irq/<IRQ#>/smp_affinity can race with the IRQ being released by QEMU, resulting in a NULL iommu pointer dereference in get_irte(), causing this crash: BUG: unable to handle kernel NULL pointer dereference at 0000000000000090 IP: [<ffffffff8190a652>] intel_ioapic_set_affinity+0x82/0x1b0 PGD 99172e067 PUD 1026979067 PMD 0 Oops: 0000 [#1] SMP Modules linked in: CPU: 1 PID: 3354 Comm: affin Not tainted 3.16.0-rc7-00007-g31dab71 #1 Hardware name: Supermicro SYS-F617R2-RT+/X9DRFR, BIOS 3.0a 01/29/2014 task: ffff881025b0e720 ti: ffff88099173c000 task.ti: ffff88099173c000 RIP: 0010:[<ffffffff8190a652>] [<ffffffff8190a652>] intel_ioapic_set_affinity+0x82/0x1b0 RSP: 0018:ffff88099173fdb0 EFLAGS: 00010046 RAX: 0000000000000082 RBX: ffff880a36294600 RCX: 0000000000000082 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8266af00 RBP: ffff88099173fdf8 R08: 0000000000000000 R09: ffff88103ec00490 R10: 0000000000000000 R11: 0000000000000000 R12: ffff88099173fe90 R13: 000000000000005f R14: ffff880faa38fe80 R15: ffff880faa38fe80 FS: 00007f7161f05740(0000) GS:ffff88107fc40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000090 CR3: 000000099140d000 CR4: 00000000001427e0 Stack: ffffffff81c44740 ffff88099173fdc8 ffffffff00000000 00000000c991fd3b ffff880a36294600 ffff88099173fe90 ffff88099173fe90 0000000000000000 0000000000000286 ffff88099173fe08 ffffffff8190aac5 ffff88099173fe28 Call Trace: [<ffffffff8190aac5>] set_remapped_irq_affinity+0x25/0x40 [<ffffffff811322dc>] irq_do_set_affinity+0x1c/0x50 [<ffffffff81132458>] irq_set_affinity_locked+0x98/0xd0 [<ffffffff811324d6>] __irq_set_affinity+0x46/0x70 [<ffffffff811362dc>] write_irq_affinity.isra.6+0xdc/0x100 [<ffffffff8113631c>] irq_affinity_list_proc_write+0x1c/0x20 [<ffffffff8129f30d>] proc_reg_write+0x3d/0x80 [<ffffffff812384a7>] vfs_write+0xb7/0x1f0 [<ffffffff81243619>] ? putname+0x29/0x40 [<ffffffff812390c5>] SyS_write+0x55/0xd0 [<ffffffff81adc729>] system_call_fastpath+0x16/0x1b Code: ff 48 85 d2 74 68 4c 8b 7a 30 4d 85 ff 74 5f 48 c7 c7 00 af 66 82 e8 9e 1b 1d 00 49 8b 57 20 41 0f b7 77 28 48 c7 c7 00 af 66 82 <48> 8b 8a 90 00 00 00 41 0f b7 57 2a 01 f2 48 89 c6 48 63 d2 48 RIP [<ffffffff8190a652>] intel_ioapic_set_affinity+0x82/0x1b0 RSP <ffff88099173fdb0> CR2: 0000000000000090 Signed-off-by: Greg Edwards <gedwards@ddn.com> Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu/intel_irq_remapping.c')
-rw-r--r--drivers/iommu/intel_irq_remapping.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index 757e0b0..0df41f6 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -70,6 +70,11 @@ static int get_irte(int irq, struct irte *entry)
raw_spin_lock_irqsave(&irq_2_ir_lock, flags);
+ if (unlikely(!irq_iommu->iommu)) {
+ raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);
+ return -1;
+ }
+
index = irq_iommu->irte_index + irq_iommu->sub_handle;
*entry = *(irq_iommu->iommu->ir_table->base + index);
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