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Groups > linux.kernel > #1702241 > unrolled thread
| Started by | Sudeep Holla <sudeep.holla@arm.com> |
|---|---|
| First post | 2017-08-02 18:20 +0200 |
| Last post | 2017-08-02 18:50 +0200 |
| Articles | 3 — 2 participants |
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[PATCH -next] iommu/of: Check for valid fwspec after of_pci_iommu_init Sudeep Holla <sudeep.holla@arm.com> - 2017-08-02 18:20 +0200
Re: [PATCH -next] iommu/of: Check for valid fwspec after of_pci_iommu_init Robin Murphy <robin.murphy@arm.com> - 2017-08-02 18:40 +0200
Re: [PATCH -next] iommu/of: Check for valid fwspec after of_pci_iommu_init Sudeep Holla <sudeep.holla@arm.com> - 2017-08-02 18:50 +0200
| From | Sudeep Holla <sudeep.holla@arm.com> |
|---|---|
| Date | 2017-08-02 18:20 +0200 |
| Subject | [PATCH -next] iommu/of: Check for valid fwspec after of_pci_iommu_init |
| Message-ID | <ua4xk-3Io-5@gated-at.bofh.it> |
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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| From | Robin Murphy <robin.murphy@arm.com> |
|---|---|
| Date | 2017-08-02 18:40 +0200 |
| Subject | Re: [PATCH -next] iommu/of: Check for valid fwspec after of_pci_iommu_init |
| Message-ID | <ua4QF-3PO-15@gated-at.bofh.it> |
| In reply to | #1702241 |
On 02/08/17 17:11, Sudeep Holla wrote:
> 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.
Ugh, a disabled IOMMU should be conceptually the same as no IOMMU, but I
guess the phandle chasing fails to fail. Per the design intent, the most
correct fix should be this:
----->8-----
diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index be8ac1ddec06..9bc83f94bc10 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -163,6 +163,8 @@ static int of_pci_iommu_init(struct pci_dev *pdev,
u16 alias, void *data)
if (IS_ERR(ops))
return PTR_ERR(ops);
+ if (!ops)
+ return 1;
return info->np == pdev->bus->dev.of_node;
}
-----8<-----
But looking again, I think an even better fix involves ripping out much
of the PTR_ERR shenanigans with ops that leads to this confusion in the
first place. Give me a moment...
Thanks,
Robin.
>
> 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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| From | Sudeep Holla <sudeep.holla@arm.com> |
|---|---|
| Date | 2017-08-02 18:50 +0200 |
| Subject | Re: [PATCH -next] iommu/of: Check for valid fwspec after of_pci_iommu_init |
| Message-ID | <ua50m-3TJ-13@gated-at.bofh.it> |
| In reply to | #1702261 |
On 02/08/17 17:39, Robin Murphy wrote:
> On 02/08/17 17:11, Sudeep Holla wrote:
>> 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.
>
> Ugh, a disabled IOMMU should be conceptually the same as no IOMMU, but I
> guess the phandle chasing fails to fail. Per the design intent, the most
> correct fix should be this:
>
> ----->8-----
> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> index be8ac1ddec06..9bc83f94bc10 100644
> --- a/drivers/iommu/of_iommu.c
> +++ b/drivers/iommu/of_iommu.c
> @@ -163,6 +163,8 @@ static int of_pci_iommu_init(struct pci_dev *pdev,
> u16 alias, void *data)
>
> if (IS_ERR(ops))
> return PTR_ERR(ops);
> + if (!ops)
> + return 1;
>
> return info->np == pdev->bus->dev.of_node;
> }
> -----8<-----
>
> But looking again, I think an even better fix involves ripping out much
> of the PTR_ERR shenanigans with ops that leads to this confusion in the
> first place. Give me a moment...
>
Sure, I will leave it to you then ;)
--
Regards,
Sudeep
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