[PATCH 1/2] cxl: fix possible null-ptr-deref in cxl_guest_init_afu|adapter()

Subsystems: char and misc drivers, the rest

STALE1373d LANDED

Landed in mainline as 61c80d1c3833 on 2022-11-23.

7 messages, 4 authors, 2022-11-30 · open the first message on its own page

[PATCH 1/2] cxl: fix possible null-ptr-deref in cxl_guest_init_afu|adapter()

From: Yang Yingliang <hidden>
Date: 2022-11-11 14:56:49

If device_register() fails in cxl_register_afu|adapter(), the device
is not added, device_unregister() can not be called in the error path,
otherwise it will cause a null-ptr-deref because of removing not added
device.

As comment of device_register() says, it should use put_device() to give
up the reference in the error path. So split device_unregister() into
device_del() and put_device(), then goes to put dev when register fails.

Fixes: 14baf4d9c739 ("cxl: Add guest-specific code")
Signed-off-by: Yang Yingliang <redacted>
---
 drivers/misc/cxl/guest.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/misc/cxl/guest.c b/drivers/misc/cxl/guest.c
index 375f692ae9d6..fb95a2d5cef4 100644
--- a/drivers/misc/cxl/guest.c
+++ b/drivers/misc/cxl/guest.c

@@ -965,10 +965,10 @@ int cxl_guest_init_afu(struct cxl *adapter, int slice, struct device_node *afu_n
 	 * if it returns an error!
 	 */
 	if ((rc = cxl_register_afu(afu)))
-		goto err_put1;
+		goto err_put_dev;
 
 	if ((rc = cxl_sysfs_afu_add(afu)))
-		goto err_put1;
+		goto err_del_dev;
 
 	/*
 	 * pHyp doesn't expose the programming models supported by the

@@ -984,7 +984,7 @@ int cxl_guest_init_afu(struct cxl *adapter, int slice, struct device_node *afu_n
 		afu->modes_supported = CXL_MODE_DIRECTED;
 
 	if ((rc = cxl_afu_select_best_mode(afu)))
-		goto err_put2;
+		goto err_remove_sysfs;
 
 	adapter->afu[afu->slice] = afu;

@@ -1004,10 +1004,12 @@ int cxl_guest_init_afu(struct cxl *adapter, int slice, struct device_node *afu_n
 
 	return 0;
 
-err_put2:
+err_remove_sysfs:
 	cxl_sysfs_afu_remove(afu);
-err_put1:
-	device_unregister(&afu->dev);
+err_del_dev:
+	device_del(&afu->dev);
+err_put_dev:
+	put_device(&afu->dev);
 	free = false;
 	guest_release_serr_irq(afu);
 err2:

@@ -1141,18 +1143,20 @@ struct cxl *cxl_guest_init_adapter(struct device_node *np, struct platform_devic
 	 * even if it returns an error!
 	 */
 	if ((rc = cxl_register_adapter(adapter)))
-		goto err_put1;
+		goto err_put_dev;
 
 	if ((rc = cxl_sysfs_adapter_add(adapter)))
-		goto err_put1;
+		goto err_del_dev;
 
 	/* release the context lock as the adapter is configured */
 	cxl_adapter_context_unlock(adapter);
 
 	return adapter;
 
-err_put1:
-	device_unregister(&adapter->dev);
+err_del_dev:
+	device_del(&adapter->dev);
+err_put_dev:
+	put_device(&adapter->dev);
 	free = false;
 	cxl_guest_remove_chardev(adapter);
 err1:

-- 
2.25.1

[PATCH 2/2] cxl: fix possible null-ptr-deref in cxl_pci_init_afu|adapter()

From: Yang Yingliang <hidden>
Date: 2022-11-11 14:57:20

If device_register() fails in cxl_pci_afu|adapter(), the device
is not added, device_unregister() can not be called in the error
path, otherwise it will cause a null-ptr-deref because of removing
not added device.

As comment of device_register() says, it should use put_device() to give
up the reference in the error path. So split device_unregister() into
device_del() and put_device(), then goes to put dev when register fails.

Fixes: f204e0b8cedd ("cxl: Driver code for powernv PCIe based cards for userspace access")
Signed-off-by: Yang Yingliang <redacted>
---
 drivers/misc/cxl/pci.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 3de0aea62ade..6d495d641c95 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c

@@ -1164,10 +1164,10 @@ static int pci_init_afu(struct cxl *adapter, int slice, struct pci_dev *dev)
 	 * if it returns an error!
 	 */
 	if ((rc = cxl_register_afu(afu)))
-		goto err_put1;
+		goto err_put_dev;
 
 	if ((rc = cxl_sysfs_afu_add(afu)))
-		goto err_put1;
+		goto err_del_dev;
 
 	adapter->afu[afu->slice] = afu;

@@ -1176,10 +1176,12 @@ static int pci_init_afu(struct cxl *adapter, int slice, struct pci_dev *dev)
 
 	return 0;
 
-err_put1:
+err_del_dev:
+	device_del(&afu->dev);
+err_put_dev:
 	pci_deconfigure_afu(afu);
 	cxl_debugfs_afu_remove(afu);
-	device_unregister(&afu->dev);
+	put_device(&afu->dev);
 	return rc;
 
 err_free_native:

@@ -1667,23 +1669,25 @@ static struct cxl *cxl_pci_init_adapter(struct pci_dev *dev)
 	 * even if it returns an error!
 	 */
 	if ((rc = cxl_register_adapter(adapter)))
-		goto err_put1;
+		goto err_put_dev;
 
 	if ((rc = cxl_sysfs_adapter_add(adapter)))
-		goto err_put1;
+		goto err_del_dev;
 
 	/* Release the context lock as adapter is configured */
 	cxl_adapter_context_unlock(adapter);
 
 	return adapter;
 
-err_put1:
+err_del_dev:
+	device_del(&adapter->dev);
+err_put_dev:
 	/* This should mirror cxl_remove_adapter, except without the
 	 * sysfs parts
 	 */
 	cxl_debugfs_adapter_remove(adapter);
 	cxl_deconfigure_adapter(adapter);
-	device_unregister(&adapter->dev);
+	put_device(&adapter->dev);
 	return ERR_PTR(rc);
 
 err_release:

-- 
2.25.1

Re: [PATCH 1/2] cxl: fix possible null-ptr-deref in cxl_guest_init_afu|adapter()

From: Frederic Barrat <hidden>
Date: 2022-11-16 18:06:14


On 11/11/2022 15:54, Yang Yingliang wrote:

If device_register() fails in cxl_register_afu|adapter(), the device
is not added, device_unregister() can not be called in the error path,
otherwise it will cause a null-ptr-deref because of removing not added
device.

As comment of device_register() says, it should use put_device() to give
up the reference in the error path. So split device_unregister() into
device_del() and put_device(), then goes to put dev when register fails.

Fixes: 14baf4d9c739 ("cxl: Add guest-specific code")
Signed-off-by: Yang Yingliang <redacted>
---


Thanks for fixing it!
At first, I was slightly uneasy about calling device_del() and 
put_device() directly, i.e. it would be better not to worry about what's 
under the hood of device_unregister(). But 1) I don't see how else to 
fix it and 2) more importantly, I looked at the history of 
device_unregister() to see how frequently it changed. I can now rest 
easy :-)

Acked-by: Frederic Barrat <redacted>

   Fred

quoted hunk

  drivers/misc/cxl/guest.c | 24 ++++++++++++++----------
  1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/misc/cxl/guest.c b/drivers/misc/cxl/guest.c
index 375f692ae9d6..fb95a2d5cef4 100644
--- a/drivers/misc/cxl/guest.c
+++ b/drivers/misc/cxl/guest.c

@@ -965,10 +965,10 @@ int cxl_guest_init_afu(struct cxl *adapter, int slice, struct device_node *afu_n
  	 * if it returns an error!
  	 */
  	if ((rc = cxl_register_afu(afu)))
-		goto err_put1;
+		goto err_put_dev;
  
  	if ((rc = cxl_sysfs_afu_add(afu)))
-		goto err_put1;
+		goto err_del_dev;
  
  	/*
  	 * pHyp doesn't expose the programming models supported by the

@@ -984,7 +984,7 @@ int cxl_guest_init_afu(struct cxl *adapter, int slice, struct device_node *afu_n
  		afu->modes_supported = CXL_MODE_DIRECTED;
  
  	if ((rc = cxl_afu_select_best_mode(afu)))
-		goto err_put2;
+		goto err_remove_sysfs;
  
  	adapter->afu[afu->slice] = afu;

@@ -1004,10 +1004,12 @@ int cxl_guest_init_afu(struct cxl *adapter, int slice, struct device_node *afu_n
  
  	return 0;
  
-err_put2:
+err_remove_sysfs:
  	cxl_sysfs_afu_remove(afu);
-err_put1:
-	device_unregister(&afu->dev);
+err_del_dev:
+	device_del(&afu->dev);
+err_put_dev:
+	put_device(&afu->dev);
  	free = false;
  	guest_release_serr_irq(afu);
  err2:

@@ -1141,18 +1143,20 @@ struct cxl *cxl_guest_init_adapter(struct device_node *np, struct platform_devic
  	 * even if it returns an error!
  	 */
  	if ((rc = cxl_register_adapter(adapter)))
-		goto err_put1;
+		goto err_put_dev;
  
  	if ((rc = cxl_sysfs_adapter_add(adapter)))
-		goto err_put1;
+		goto err_del_dev;
  
  	/* release the context lock as the adapter is configured */
  	cxl_adapter_context_unlock(adapter);
  
  	return adapter;
  
-err_put1:
-	device_unregister(&adapter->dev);
+err_del_dev:
+	device_del(&adapter->dev);
+err_put_dev:
+	put_device(&adapter->dev);
  	free = false;
  	cxl_guest_remove_chardev(adapter);
  err1:

Re: [PATCH 2/2] cxl: fix possible null-ptr-deref in cxl_pci_init_afu|adapter()

From: Frederic Barrat <hidden>
Date: 2022-11-16 18:08:44


On 11/11/2022 15:54, Yang Yingliang wrote:

If device_register() fails in cxl_pci_afu|adapter(), the device
is not added, device_unregister() can not be called in the error
path, otherwise it will cause a null-ptr-deref because of removing
not added device.

As comment of device_register() says, it should use put_device() to give
up the reference in the error path. So split device_unregister() into
device_del() and put_device(), then goes to put dev when register fails.

Fixes: f204e0b8cedd ("cxl: Driver code for powernv PCIe based cards for userspace access")
Signed-off-by: Yang Yingliang <redacted>
---


Acked-by: Frederic Barrat <redacted>

   Fred

quoted hunk

  drivers/misc/cxl/pci.c | 20 ++++++++++++--------
  1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 3de0aea62ade..6d495d641c95 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c

@@ -1164,10 +1164,10 @@ static int pci_init_afu(struct cxl *adapter, int slice, struct pci_dev *dev)
  	 * if it returns an error!
  	 */
  	if ((rc = cxl_register_afu(afu)))
-		goto err_put1;
+		goto err_put_dev;
  
  	if ((rc = cxl_sysfs_afu_add(afu)))
-		goto err_put1;
+		goto err_del_dev;
  
  	adapter->afu[afu->slice] = afu;

@@ -1176,10 +1176,12 @@ static int pci_init_afu(struct cxl *adapter, int slice, struct pci_dev *dev)
  
  	return 0;
  
-err_put1:
+err_del_dev:
+	device_del(&afu->dev);
+err_put_dev:
  	pci_deconfigure_afu(afu);
  	cxl_debugfs_afu_remove(afu);
-	device_unregister(&afu->dev);
+	put_device(&afu->dev);
  	return rc;
  
  err_free_native:

@@ -1667,23 +1669,25 @@ static struct cxl *cxl_pci_init_adapter(struct pci_dev *dev)
  	 * even if it returns an error!
  	 */
  	if ((rc = cxl_register_adapter(adapter)))
-		goto err_put1;
+		goto err_put_dev;
  
  	if ((rc = cxl_sysfs_adapter_add(adapter)))
-		goto err_put1;
+		goto err_del_dev;
  
  	/* Release the context lock as adapter is configured */
  	cxl_adapter_context_unlock(adapter);
  
  	return adapter;
  
-err_put1:
+err_del_dev:
+	device_del(&adapter->dev);
+err_put_dev:
  	/* This should mirror cxl_remove_adapter, except without the
  	 * sysfs parts
  	 */
  	cxl_debugfs_adapter_remove(adapter);
  	cxl_deconfigure_adapter(adapter);
-	device_unregister(&adapter->dev);
+	put_device(&adapter->dev);
  	return ERR_PTR(rc);
  
  err_release:

Re: [PATCH 1/2] cxl: fix possible null-ptr-deref in cxl_guest_init_afu|adapter()

From: Andrew Donnellan <hidden>
Date: 2022-11-21 05:20:14

On Fri, 2022-11-11 at 22:54 +0800, Yang Yingliang wrote:

If device_register() fails in cxl_register_afu|adapter(), the device
is not added, device_unregister() can not be called in the error
path,
otherwise it will cause a null-ptr-deref because of removing not
added
device.

As comment of device_register() says, it should use put_device() to
give
up the reference in the error path. So split device_unregister() into
device_del() and put_device(), then goes to put dev when register
fails.

The comment around device_add() is relevant too:

  Rule of thumb is: if device_add() succeeds, you should call
  device_del() when you want to get rid of it. If device_add() has
  *not* succeeded, use *only* put_device() to drop the reference count.

Fixes: 14baf4d9c739 ("cxl: Add guest-specific code")
Signed-off-by: Yang Yingliang <redacted>

Thanks for the fix!

Acked-by: Andrew Donnellan <redacted>

quoted hunk

---
 drivers/misc/cxl/guest.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/misc/cxl/guest.c b/drivers/misc/cxl/guest.c
index 375f692ae9d6..fb95a2d5cef4 100644
--- a/drivers/misc/cxl/guest.c
+++ b/drivers/misc/cxl/guest.c

@@ -965,10 +965,10 @@ int cxl_guest_init_afu(struct cxl *adapter, int

slice, struct device_node *afu_n
         * if it returns an error!
         */
        if ((rc = cxl_register_afu(afu)))
-               goto err_put1;
+               goto err_put_dev;
 
        if ((rc = cxl_sysfs_afu_add(afu)))
-               goto err_put1;
+               goto err_del_dev;
 
        /*
         * pHyp doesn't expose the programming models supported by
the

@@ -984,7 +984,7 @@ int cxl_guest_init_afu(struct cxl *adapter, int

slice, struct device_node *afu_n
                afu->modes_supported = CXL_MODE_DIRECTED;
 
        if ((rc = cxl_afu_select_best_mode(afu)))
-               goto err_put2;
+               goto err_remove_sysfs;
 
        adapter->afu[afu->slice] = afu;

@@ -1004,10 +1004,12 @@ int cxl_guest_init_afu(struct cxl *adapter,

int slice, struct device_node *afu_n
 
        return 0;
 
-err_put2:
+err_remove_sysfs:
        cxl_sysfs_afu_remove(afu);
-err_put1:
-       device_unregister(&afu->dev);
+err_del_dev:
+       device_del(&afu->dev);
+err_put_dev:
+       put_device(&afu->dev);
        free = false;
        guest_release_serr_irq(afu);
 err2:

@@ -1141,18 +1143,20 @@ struct cxl *cxl_guest_init_adapter(struct

device_node *np, struct platform_devic
         * even if it returns an error!
         */
        if ((rc = cxl_register_adapter(adapter)))
-               goto err_put1;
+               goto err_put_dev;
 
        if ((rc = cxl_sysfs_adapter_add(adapter)))
-               goto err_put1;
+               goto err_del_dev;
 
        /* release the context lock as the adapter is configured */
        cxl_adapter_context_unlock(adapter);
 
        return adapter;
 
-err_put1:
-       device_unregister(&adapter->dev);
+err_del_dev:
+       device_del(&adapter->dev);
+err_put_dev:
+       put_device(&adapter->dev);
        free = false;
        cxl_guest_remove_chardev(adapter);
 err1:

-- 
Andrew Donnellan    OzLabs, ADL Canberra
ajd@linux.ibm.com   IBM Australia Limited

Re: [PATCH 2/2] cxl: fix possible null-ptr-deref in cxl_pci_init_afu|adapter()

From: Andrew Donnellan <hidden>
Date: 2022-11-21 05:36:34

On Fri, 2022-11-11 at 22:54 +0800, Yang Yingliang wrote:

If device_register() fails in cxl_pci_afu|adapter(), the device
is not added, device_unregister() can not be called in the error
path, otherwise it will cause a null-ptr-deref because of removing
not added device.

As comment of device_register() says, it should use put_device() to
give
up the reference in the error path. So split device_unregister() into
device_del() and put_device(), then goes to put dev when register
fails.

Fixes: f204e0b8cedd ("cxl: Driver code for powernv PCIe based cards
for userspace access")
Signed-off-by: Yang Yingliang <redacted>

See reply to patch #1.

This patch puts a few things between the device_del() call and the
put_device() call, but that looks fine - we don't touch afu->dev in the
middle.

Thanks for the fix!

Acked-by: Andrew Donnellan <redacted>

quoted hunk

---
 drivers/misc/cxl/pci.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 3de0aea62ade..6d495d641c95 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c

@@ -1164,10 +1164,10 @@ static int pci_init_afu(struct cxl *adapter,

int slice, struct pci_dev *dev)
         * if it returns an error!
         */
        if ((rc = cxl_register_afu(afu)))
-               goto err_put1;
+               goto err_put_dev;
 
        if ((rc = cxl_sysfs_afu_add(afu)))
-               goto err_put1;
+               goto err_del_dev;
 
        adapter->afu[afu->slice] = afu;

@@ -1176,10 +1176,12 @@ static int pci_init_afu(struct cxl *adapter,

int slice, struct pci_dev *dev)
 
        return 0;
 
-err_put1:
+err_del_dev:
+       device_del(&afu->dev);
+err_put_dev:
        pci_deconfigure_afu(afu);
        cxl_debugfs_afu_remove(afu);
-       device_unregister(&afu->dev);
+       put_device(&afu->dev);
        return rc;
 
 err_free_native:

@@ -1667,23 +1669,25 @@ static struct cxl

*cxl_pci_init_adapter(struct pci_dev *dev)
         * even if it returns an error!
         */
        if ((rc = cxl_register_adapter(adapter)))
-               goto err_put1;
+               goto err_put_dev;
 
        if ((rc = cxl_sysfs_adapter_add(adapter)))
-               goto err_put1;
+               goto err_del_dev;
 
        /* Release the context lock as adapter is configured */
        cxl_adapter_context_unlock(adapter);
 
        return adapter;
 
-err_put1:
+err_del_dev:
+       device_del(&adapter->dev);
+err_put_dev:
        /* This should mirror cxl_remove_adapter, except without the
         * sysfs parts
         */
        cxl_debugfs_adapter_remove(adapter);
        cxl_deconfigure_adapter(adapter);
-       device_unregister(&adapter->dev);
+       put_device(&adapter->dev);
        return ERR_PTR(rc);
 
 err_release:

-- 
Andrew Donnellan    OzLabs, ADL Canberra
ajd@linux.ibm.com   IBM Australia Limited

Re: [PATCH 1/2] cxl: fix possible null-ptr-deref in cxl_guest_init_afu|adapter()

From: Michael Ellerman <hidden>
Date: 2022-11-30 09:52:33

On Fri, 11 Nov 2022 22:54:39 +0800, Yang Yingliang wrote:

If device_register() fails in cxl_register_afu|adapter(), the device
is not added, device_unregister() can not be called in the error path,
otherwise it will cause a null-ptr-deref because of removing not added
device.

As comment of device_register() says, it should use put_device() to give
up the reference in the error path. So split device_unregister() into
device_del() and put_device(), then goes to put dev when register fails.

[...]

Applied to powerpc/next.

[1/2] cxl: fix possible null-ptr-deref in cxl_guest_init_afu|adapter()
      https://git.kernel.org/powerpc/c/f949ccee1dde970bc77dc871b4f0b5e651577344
[2/2] cxl: fix possible null-ptr-deref in cxl_pci_init_afu|adapter()
      https://git.kernel.org/powerpc/c/8bf03f557d6c6e108cf47bea32f4a68e276e1157

cheers

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