Messages in this thread Patch in this message | | | From | Sudeep Holla <> | Subject | [PATCH -next] iommu/of: Check for valid fwspec after of_pci_iommu_init | Date | Wed, 2 Aug 2017 17:11:40 +0100 |
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The successful return from of_pci_iommu_init doesn't ensure valid fwspec if it's IOMMU is disabled.
Accessing dev->iommu_fwspec->ops without checking dev->iommu_fwspec could result in NULL pointer dereference.
Unable to handle kernel NULL pointer dereference at virtual address 00000000 task: ffff800976880000 task.stack: ffff800976888000 PC is at of_iommu_configure+0x130/0x138 LR is at of_iommu_configure+0x118/0x138 of_iommu_configure+0x130/0x138 of_dma_configure+0xa8/0x190 dma_configure+0x40/0xe8 driver_probe_device+0x190/0x2d0 __device_attach_driver+0x9c/0xf8 bus_for_each_drv+0x58/0x98 __device_attach+0xc4/0x138 device_attach+0x10/0x18 pci_bus_add_device+0x4c/0xa8 pci_bus_add_devices+0x44/0x90 pci_bus_add_devices+0x74/0x90 pci_host_common_probe+0x14c/0x3a8 gen_pci_probe+0x2c/0x38 platform_drv_probe+0x58/0xc0 driver_probe_device+0x214/0x2d0 __driver_attach+0xac/0xb0 bus_for_each_dev+0x60/0xa0 driver_attach+0x20/0x28 bus_add_driver+0x110/0x230 driver_register+0x60/0xf8 __platform_driver_register+0x44/0x50 gen_pci_driver_init+0x18/0x20 do_one_initcall+0x38/0x120 kernel_init_freeable+0x184/0x224 kernel_init+0x10/0x100
This patch adds the check for dev->iommu_fwspec and fixes the above.
Fixes: d87beb749281 ("iommu/of: Handle PCI aliases properly") Cc: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> --- drivers/iommu/of_iommu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
Hi Robin,
I see this crash on Juno with linux-next. Enabling PCIe SMMU fixes the issue, but we may need to handle the disabled SMMU case to continue to work with old DTBs.
Regards, Sudeep
diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c index 34160e7a8dd7..11e08ff2db57 100644 --- a/drivers/iommu/of_iommu.c +++ b/drivers/iommu/of_iommu.c @@ -200,7 +200,8 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, of_pci_iommu_init, &info); if (err) /* err > 0 means the walk stopped, but non-fatally */ ops = ERR_PTR(min(err, 0)); - else /* success implies both fwspec and ops are now valid */ + /* success may not imply fwspec is valid */ + else if (dev->iommu_fwspec) ops = dev->iommu_fwspec->ops; } else { struct of_phandle_args iommu_spec; -- 2.7.4
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