| Message ID | 20221111145440.2426970-1-yangyingliang@huawei.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | f949ccee1dde970bc77dc871b4f0b5e651577344 |
| Headers | show |
| Series | [1/2] cxl: fix possible null-ptr-deref in cxl_guest_init_afu|adapter() | expand |
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 <yangyingliang@huawei.com> > --- 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 <fbarrat@linux.ibm.com> Fred > 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:
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 <yangyingliang@huawei.com> Thanks for the fix! Acked-by: Andrew Donnellan <ajd@linux.ibm.com> > --- > 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:
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
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:
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 <yangyingliang@huawei.com> --- drivers/misc/cxl/guest.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-)