[PATCH v2] PCI: designware-ep: Fix the reference to pci->num_{ib,ob}_windows before setting

[PATCH v2] PCI: designware-ep: Fix the reference to pci->num_{ib,ob}_windows before setting

[Kunihiko Hayashi]

The commit 281f1f99cf3a ("PCI: dwc: Detect number of iATU windows") gets
the values of pci->num_ib_windows and pci->num_ob_windows from iATU
registers instead of DT properties in dw_pcie_iatu_detect_regions*() or its
unroll version.

However, before the values are set, the allocations in dw_pcie_ep_init()
refer them to determine the sizes of window_map. As a result, null pointer
dereference exception will occur when linking the EP function and the
controller.

  # ln -s functions/pci_epf_test/test controllers/66000000.pcie-ep/
  Unable to handle kernel NULL pointer dereference at virtual address
  0000000000000010

The call trace is as follows:

  Call trace:
   _find_next_bit.constprop.1+0xc/0x88
   dw_pcie_ep_set_bar+0x78/0x1f8
   pci_epc_set_bar+0x9c/0xe8
   pci_epf_test_core_init+0xe8/0x220
   pci_epf_test_bind+0x1e0/0x378
   pci_epf_bind+0x54/0xb0
   pci_epc_epf_link+0x58/0x80
   configfs_symlink+0x1c0/0x570
   vfs_symlink+0xdc/0x198
   do_symlinkat+0xa0/0x110
   __arm64_sys_symlinkat+0x28/0x38
   el0_svc_common+0x84/0x1a0
   do_el0_svc+0x38/0x88
   el0_svc+0x1c/0x28
   el0_sync_handler+0x88/0xb0
   el0_sync+0x140/0x180

The pci->num_{ib,ob}_windows should be referenced after they are set by
dw_pcie_iatu_detect_regions*() called from dw_pcie_setup().

Cc: Rob Herring <robh@kernel.org>
Fixes: 281f1f99cf3a ("PCI: dwc: Detect number of iATU windows")
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
---
 drivers/pci/controller/dwc/pcie-designware-ep.c | 41 ++++++++++++-------------
 1 file changed, 20 insertions(+), 21 deletions(-)

Changed since v1:
- Add description of exception to commit message
- Change the subject

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index bcd1cd9..adc7ca5 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -638,6 +638,7 @@ static unsigned int dw_pcie_ep_find_ext_capability(struct dw_pcie *pci, int cap)
 int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+	struct device *dev = pci->dev;
 	unsigned int offset;
 	unsigned int nbars;
 	u8 hdr_type;
@@ -669,6 +670,25 @@ int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
 	dw_pcie_setup(pci);
 	dw_pcie_dbi_ro_wr_dis(pci);
 
+	ep->ib_window_map = devm_kcalloc(dev,
+					 BITS_TO_LONGS(pci->num_ib_windows),
+					 sizeof(long),
+					 GFP_KERNEL);
+	if (!ep->ib_window_map)
+		return -ENOMEM;
+
+	ep->ob_window_map = devm_kcalloc(dev,
+					 BITS_TO_LONGS(pci->num_ob_windows),
+					 sizeof(long),
+					 GFP_KERNEL);
+	if (!ep->ob_window_map)
+		return -ENOMEM;
+
+	ep->outbound_addr = devm_kcalloc(dev, pci->num_ob_windows, sizeof(phys_addr_t),
+			    GFP_KERNEL);
+	if (!ep->outbound_addr)
+		return -ENOMEM;
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(dw_pcie_ep_init_complete);
@@ -676,7 +696,6 @@ EXPORT_SYMBOL_GPL(dw_pcie_ep_init_complete);
 int dw_pcie_ep_init(struct dw_pcie_ep *ep)
 {
 	int ret;
-	void *addr;
 	u8 func_no;
 	struct resource *res;
 	struct pci_epc *epc;
@@ -714,26 +733,6 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
 	ep->phys_base = res->start;
 	ep->addr_size = resource_size(res);
 
-	ep->ib_window_map = devm_kcalloc(dev,
-					 BITS_TO_LONGS(pci->num_ib_windows),
-					 sizeof(long),
-					 GFP_KERNEL);
-	if (!ep->ib_window_map)
-		return -ENOMEM;
-
-	ep->ob_window_map = devm_kcalloc(dev,
-					 BITS_TO_LONGS(pci->num_ob_windows),
-					 sizeof(long),
-					 GFP_KERNEL);
-	if (!ep->ob_window_map)
-		return -ENOMEM;
-
-	addr = devm_kcalloc(dev, pci->num_ob_windows, sizeof(phys_addr_t),
-			    GFP_KERNEL);
-	if (!addr)
-		return -ENOMEM;
-	ep->outbound_addr = addr;
-
 	if (pci->link_gen < 1)
 		pci->link_gen = of_pci_get_max_link_speed(np);
 
-- 
2.7.4

Re: [PATCH v2] PCI: designware-ep: Fix the reference to pci->num_{ib,ob}_windows before setting

[Rob Herring]

On Mon, Jan 18, 2021 at 5:10 PM Kunihiko Hayashi
<hayashi.kunihiko@socionext.com> wrote:
>
> The commit 281f1f99cf3a ("PCI: dwc: Detect number of iATU windows") gets
> the values of pci->num_ib_windows and pci->num_ob_windows from iATU
> registers instead of DT properties in dw_pcie_iatu_detect_regions*() or its
> unroll version.
>
> However, before the values are set, the allocations in dw_pcie_ep_init()
> refer them to determine the sizes of window_map. As a result, null pointer
> dereference exception will occur when linking the EP function and the
> controller.
>
>   # ln -s functions/pci_epf_test/test controllers/66000000.pcie-ep/
>   Unable to handle kernel NULL pointer dereference at virtual address
>   0000000000000010
>
> The call trace is as follows:
>
>   Call trace:
>    _find_next_bit.constprop.1+0xc/0x88
>    dw_pcie_ep_set_bar+0x78/0x1f8
>    pci_epc_set_bar+0x9c/0xe8
>    pci_epf_test_core_init+0xe8/0x220
>    pci_epf_test_bind+0x1e0/0x378
>    pci_epf_bind+0x54/0xb0
>    pci_epc_epf_link+0x58/0x80
>    configfs_symlink+0x1c0/0x570
>    vfs_symlink+0xdc/0x198
>    do_symlinkat+0xa0/0x110
>    __arm64_sys_symlinkat+0x28/0x38
>    el0_svc_common+0x84/0x1a0
>    do_el0_svc+0x38/0x88
>    el0_svc+0x1c/0x28
>    el0_sync_handler+0x88/0xb0
>    el0_sync+0x140/0x180
>
> The pci->num_{ib,ob}_windows should be referenced after they are set by
> dw_pcie_iatu_detect_regions*() called from dw_pcie_setup().
>
> Cc: Rob Herring <robh@kernel.org>
> Fixes: 281f1f99cf3a ("PCI: dwc: Detect number of iATU windows")
> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware-ep.c | 41 ++++++++++++-------------
>  1 file changed, 20 insertions(+), 21 deletions(-)

Reviewed-by: Rob Herring <robh@kernel.org>

Re: [PATCH v2] PCI: designware-ep: Fix the reference to pci->num_{ib,ob}_windows before setting

[Kunihiko Hayashi]

Cc: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>

I found that this patch would cause null pointer dereference exception
when removing the function link.

If once linking the test function to the controller,
   # ln -s functions/pci_epf_test/test controllers/66000000.pcie-ep/

and unlinking it immediately,
   # rm controllers/66000000.pcie-ep/test

then the driver will occur null pointer access in dw_pcie_ep_clear_bar()
because ep->ib_window_map doesn't have a pointer to allocated memory yet.

To fix the original issue, I strongly recommend to apply Hou's patch [1]
instead of this patch.

Thank you,

[1] https://patchwork.kernel.org/project/linux-pci/patch/20210125044803.4310-1-Zhiqiang.Hou@nxp.com/

On 2021/01/21 0:20, Rob Herring wrote:
> On Mon, Jan 18, 2021 at 5:10 PM Kunihiko Hayashi
> <hayashi.kunihiko@socionext.com> wrote:
>>
>> The commit 281f1f99cf3a ("PCI: dwc: Detect number of iATU windows") gets
>> the values of pci->num_ib_windows and pci->num_ob_windows from iATU
>> registers instead of DT properties in dw_pcie_iatu_detect_regions*() or its
>> unroll version.
>>
>> However, before the values are set, the allocations in dw_pcie_ep_init()
>> refer them to determine the sizes of window_map. As a result, null pointer
>> dereference exception will occur when linking the EP function and the
>> controller.
>>
>>    # ln -s functions/pci_epf_test/test controllers/66000000.pcie-ep/
>>    Unable to handle kernel NULL pointer dereference at virtual address
>>    0000000000000010
>>
>> The call trace is as follows:
>>
>>    Call trace:
>>     _find_next_bit.constprop.1+0xc/0x88
>>     dw_pcie_ep_set_bar+0x78/0x1f8
>>     pci_epc_set_bar+0x9c/0xe8
>>     pci_epf_test_core_init+0xe8/0x220
>>     pci_epf_test_bind+0x1e0/0x378
>>     pci_epf_bind+0x54/0xb0
>>     pci_epc_epf_link+0x58/0x80
>>     configfs_symlink+0x1c0/0x570
>>     vfs_symlink+0xdc/0x198
>>     do_symlinkat+0xa0/0x110
>>     __arm64_sys_symlinkat+0x28/0x38
>>     el0_svc_common+0x84/0x1a0
>>     do_el0_svc+0x38/0x88
>>     el0_svc+0x1c/0x28
>>     el0_sync_handler+0x88/0xb0
>>     el0_sync+0x140/0x180
>>
>> The pci->num_{ib,ob}_windows should be referenced after they are set by
>> dw_pcie_iatu_detect_regions*() called from dw_pcie_setup().
>>
>> Cc: Rob Herring <robh@kernel.org>
>> Fixes: 281f1f99cf3a ("PCI: dwc: Detect number of iATU windows")
>> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
>> ---
>>   drivers/pci/controller/dwc/pcie-designware-ep.c | 41 ++++++++++++-------------
>>   1 file changed, 20 insertions(+), 21 deletions(-)
> 
> Reviewed-by: Rob Herring <robh@kernel.org>
> 

-- 
---
Best Regards
Kunihiko Hayashi