Currently it's possible to iterate over the dangling pointer in case the device
suddenly disappears. This may happen becase callers put it at the end of a loop.
Instead, let's move that call inside acpi_dev_get_next_match_dev().
Fixes: 803abec64ef9 ("media: ipu3-cio2: Add cio2-bridge to ipu3-cio2 driver")
Fixes: bf263f64e804 ("media: ACPI / bus: Add acpi_dev_get_next_match_dev() and helper macro")
Fixes: edbd1bc4951e ("efi/dev-path-parser: Switch to use for_each_acpi_dev_match()")
Signed-off-by: Andy Shevchenko <[email protected]>
---
v2:
- rebased on top of v5.14-rc1 and hence added fix for EFI code
- added kernel documentation update to point out that
acpi_dev_get_next_match_dev() drops a reference on the given
ACPI device (Rafael)
drivers/acpi/utils.c | 7 +++----
drivers/firmware/efi/dev-path-parser.c | 1 -
drivers/media/pci/intel/ipu3/cio2-bridge.c | 6 ++----
include/acpi/acpi_bus.h | 5 -----
4 files changed, 5 insertions(+), 14 deletions(-)
diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index e7ddd281afff..d5cedffeeff9 100644
--- a/drivers/acpi/utils.c
+++ b/drivers/acpi/utils.c
@@ -860,11 +860,9 @@ EXPORT_SYMBOL(acpi_dev_present);
* Return the next match of ACPI device if another matching device was present
* at the moment of invocation, or NULL otherwise.
*
- * FIXME: The function does not tolerate the sudden disappearance of @adev, e.g.
- * in the case of a hotplug event. That said, the caller should ensure that
- * this will never happen.
- *
* The caller is responsible for invoking acpi_dev_put() on the returned device.
+ * On the other hand the function invokes acpi_dev_put() on the given @adev
+ * assuming that its reference counter had been increased beforehand.
*
* See additional information in acpi_dev_present() as well.
*/
@@ -880,6 +878,7 @@ acpi_dev_get_next_match_dev(struct acpi_device *adev, const char *hid, const cha
match.hrv = hrv;
dev = bus_find_device(&acpi_bus_type, start, &match, acpi_dev_match_cb);
+ acpi_dev_put(adev);
return dev ? to_acpi_device(dev) : NULL;
}
EXPORT_SYMBOL(acpi_dev_get_next_match_dev);
diff --git a/drivers/firmware/efi/dev-path-parser.c b/drivers/firmware/efi/dev-path-parser.c
index 10d4457417a4..eb9c65f97841 100644
--- a/drivers/firmware/efi/dev-path-parser.c
+++ b/drivers/firmware/efi/dev-path-parser.c
@@ -34,7 +34,6 @@ static long __init parse_acpi_path(const struct efi_dev_path *node,
break;
if (!adev->pnp.unique_id && node->acpi.uid == 0)
break;
- acpi_dev_put(adev);
}
if (!adev)
return -ENODEV;
diff --git a/drivers/media/pci/intel/ipu3/cio2-bridge.c b/drivers/media/pci/intel/ipu3/cio2-bridge.c
index 4657e99df033..59a36f922675 100644
--- a/drivers/media/pci/intel/ipu3/cio2-bridge.c
+++ b/drivers/media/pci/intel/ipu3/cio2-bridge.c
@@ -173,10 +173,8 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg,
int ret;
for_each_acpi_dev_match(adev, cfg->hid, NULL, -1) {
- if (!adev->status.enabled) {
- acpi_dev_put(adev);
+ if (!adev->status.enabled)
continue;
- }
if (bridge->n_sensors >= CIO2_NUM_PORTS) {
acpi_dev_put(adev);
@@ -185,7 +183,6 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg,
}
sensor = &bridge->sensors[bridge->n_sensors];
- sensor->adev = adev;
strscpy(sensor->name, cfg->hid, sizeof(sensor->name));
ret = cio2_bridge_read_acpi_buffer(adev, "SSDB",
@@ -215,6 +212,7 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg,
goto err_free_swnodes;
}
+ sensor->adev = acpi_dev_get(adev);
adev->fwnode.secondary = fwnode;
dev_info(&cio2->dev, "Found supported sensor %s\n",
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 1ae993fee4a5..b9d434a93632 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -707,11 +707,6 @@ acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv);
* @hrv: Hardware Revision of the device, pass -1 to not check _HRV
*
* The caller is responsible for invoking acpi_dev_put() on the returned device.
- *
- * FIXME: Due to above requirement there is a window that may invalidate @adev
- * and next iteration will use a dangling pointer, e.g. in the case of a
- * hotplug event. That said, the caller should ensure that this will never
- * happen.
*/
#define for_each_acpi_dev_match(adev, hid, uid, hrv) \
for (adev = acpi_dev_get_first_match_dev(hid, uid, hrv); \
--
2.32.0
Hi Andy - thanks for fixing this
On 12/07/2021 19:21, Andy Shevchenko wrote:
> Currently it's possible to iterate over the dangling pointer in case the device
> suddenly disappears. This may happen becase callers put it at the end of a loop.
>
> Instead, let's move that call inside acpi_dev_get_next_match_dev().
>
> Fixes: 803abec64ef9 ("media: ipu3-cio2: Add cio2-bridge to ipu3-cio2 driver")
> Fixes: bf263f64e804 ("media: ACPI / bus: Add acpi_dev_get_next_match_dev() and helper macro")
> Fixes: edbd1bc4951e ("efi/dev-path-parser: Switch to use for_each_acpi_dev_match()")
> Signed-off-by: Andy Shevchenko <[email protected]>
Reviewed-by: Daniel Scally <[email protected]>
> ---
> v2:
> - rebased on top of v5.14-rc1 and hence added fix for EFI code
> - added kernel documentation update to point out that
> acpi_dev_get_next_match_dev() drops a reference on the given
> ACPI device (Rafael)
>
> drivers/acpi/utils.c | 7 +++----
> drivers/firmware/efi/dev-path-parser.c | 1 -
> drivers/media/pci/intel/ipu3/cio2-bridge.c | 6 ++----
> include/acpi/acpi_bus.h | 5 -----
> 4 files changed, 5 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
> index e7ddd281afff..d5cedffeeff9 100644
> --- a/drivers/acpi/utils.c
> +++ b/drivers/acpi/utils.c
> @@ -860,11 +860,9 @@ EXPORT_SYMBOL(acpi_dev_present);
> * Return the next match of ACPI device if another matching device was present
> * at the moment of invocation, or NULL otherwise.
> *
> - * FIXME: The function does not tolerate the sudden disappearance of @adev, e.g.
> - * in the case of a hotplug event. That said, the caller should ensure that
> - * this will never happen.
> - *
> * The caller is responsible for invoking acpi_dev_put() on the returned device.
> + * On the other hand the function invokes acpi_dev_put() on the given @adev
> + * assuming that its reference counter had been increased beforehand.
> *
> * See additional information in acpi_dev_present() as well.
> */
> @@ -880,6 +878,7 @@ acpi_dev_get_next_match_dev(struct acpi_device *adev, const char *hid, const cha
> match.hrv = hrv;
>
> dev = bus_find_device(&acpi_bus_type, start, &match, acpi_dev_match_cb);
> + acpi_dev_put(adev);
> return dev ? to_acpi_device(dev) : NULL;
> }
> EXPORT_SYMBOL(acpi_dev_get_next_match_dev);
> diff --git a/drivers/firmware/efi/dev-path-parser.c b/drivers/firmware/efi/dev-path-parser.c
> index 10d4457417a4..eb9c65f97841 100644
> --- a/drivers/firmware/efi/dev-path-parser.c
> +++ b/drivers/firmware/efi/dev-path-parser.c
> @@ -34,7 +34,6 @@ static long __init parse_acpi_path(const struct efi_dev_path *node,
> break;
> if (!adev->pnp.unique_id && node->acpi.uid == 0)
> break;
> - acpi_dev_put(adev);
> }
> if (!adev)
> return -ENODEV;
> diff --git a/drivers/media/pci/intel/ipu3/cio2-bridge.c b/drivers/media/pci/intel/ipu3/cio2-bridge.c
> index 4657e99df033..59a36f922675 100644
> --- a/drivers/media/pci/intel/ipu3/cio2-bridge.c
> +++ b/drivers/media/pci/intel/ipu3/cio2-bridge.c
> @@ -173,10 +173,8 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg,
> int ret;
>
> for_each_acpi_dev_match(adev, cfg->hid, NULL, -1) {
> - if (!adev->status.enabled) {
> - acpi_dev_put(adev);
> + if (!adev->status.enabled)
> continue;
> - }
>
> if (bridge->n_sensors >= CIO2_NUM_PORTS) {
> acpi_dev_put(adev);
> @@ -185,7 +183,6 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg,
> }
>
> sensor = &bridge->sensors[bridge->n_sensors];
> - sensor->adev = adev;
> strscpy(sensor->name, cfg->hid, sizeof(sensor->name));
>
> ret = cio2_bridge_read_acpi_buffer(adev, "SSDB",
> @@ -215,6 +212,7 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg,
> goto err_free_swnodes;
> }
>
> + sensor->adev = acpi_dev_get(adev);
> adev->fwnode.secondary = fwnode;
>
> dev_info(&cio2->dev, "Found supported sensor %s\n",
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index 1ae993fee4a5..b9d434a93632 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -707,11 +707,6 @@ acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv);
> * @hrv: Hardware Revision of the device, pass -1 to not check _HRV
> *
> * The caller is responsible for invoking acpi_dev_put() on the returned device.
> - *
> - * FIXME: Due to above requirement there is a window that may invalidate @adev
> - * and next iteration will use a dangling pointer, e.g. in the case of a
> - * hotplug event. That said, the caller should ensure that this will never
> - * happen.
> */
> #define for_each_acpi_dev_match(adev, hid, uid, hrv) \
> for (adev = acpi_dev_get_first_match_dev(hid, uid, hrv); \
On Wed, Jul 14, 2021 at 12:32 AM Daniel Scally <[email protected]> wrote:
>
> Hi Andy - thanks for fixing this
>
> On 12/07/2021 19:21, Andy Shevchenko wrote:
> > Currently it's possible to iterate over the dangling pointer in case the device
> > suddenly disappears. This may happen becase callers put it at the end of a loop.
> >
> > Instead, let's move that call inside acpi_dev_get_next_match_dev().
> >
> > Fixes: 803abec64ef9 ("media: ipu3-cio2: Add cio2-bridge to ipu3-cio2 driver")
> > Fixes: bf263f64e804 ("media: ACPI / bus: Add acpi_dev_get_next_match_dev() and helper macro")
> > Fixes: edbd1bc4951e ("efi/dev-path-parser: Switch to use for_each_acpi_dev_match()")
> > Signed-off-by: Andy Shevchenko <[email protected]>
>
> Reviewed-by: Daniel Scally <[email protected]>
Applied as 5.14-rc material, thanks!
> > ---
> > v2:
> > - rebased on top of v5.14-rc1 and hence added fix for EFI code
> > - added kernel documentation update to point out that
> > acpi_dev_get_next_match_dev() drops a reference on the given
> > ACPI device (Rafael)
> >
> > drivers/acpi/utils.c | 7 +++----
> > drivers/firmware/efi/dev-path-parser.c | 1 -
> > drivers/media/pci/intel/ipu3/cio2-bridge.c | 6 ++----
> > include/acpi/acpi_bus.h | 5 -----
> > 4 files changed, 5 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
> > index e7ddd281afff..d5cedffeeff9 100644
> > --- a/drivers/acpi/utils.c
> > +++ b/drivers/acpi/utils.c
> > @@ -860,11 +860,9 @@ EXPORT_SYMBOL(acpi_dev_present);
> > * Return the next match of ACPI device if another matching device was present
> > * at the moment of invocation, or NULL otherwise.
> > *
> > - * FIXME: The function does not tolerate the sudden disappearance of @adev, e.g.
> > - * in the case of a hotplug event. That said, the caller should ensure that
> > - * this will never happen.
> > - *
> > * The caller is responsible for invoking acpi_dev_put() on the returned device.
> > + * On the other hand the function invokes acpi_dev_put() on the given @adev
> > + * assuming that its reference counter had been increased beforehand.
> > *
> > * See additional information in acpi_dev_present() as well.
> > */
> > @@ -880,6 +878,7 @@ acpi_dev_get_next_match_dev(struct acpi_device *adev, const char *hid, const cha
> > match.hrv = hrv;
> >
> > dev = bus_find_device(&acpi_bus_type, start, &match, acpi_dev_match_cb);
> > + acpi_dev_put(adev);
> > return dev ? to_acpi_device(dev) : NULL;
> > }
> > EXPORT_SYMBOL(acpi_dev_get_next_match_dev);
> > diff --git a/drivers/firmware/efi/dev-path-parser.c b/drivers/firmware/efi/dev-path-parser.c
> > index 10d4457417a4..eb9c65f97841 100644
> > --- a/drivers/firmware/efi/dev-path-parser.c
> > +++ b/drivers/firmware/efi/dev-path-parser.c
> > @@ -34,7 +34,6 @@ static long __init parse_acpi_path(const struct efi_dev_path *node,
> > break;
> > if (!adev->pnp.unique_id && node->acpi.uid == 0)
> > break;
> > - acpi_dev_put(adev);
> > }
> > if (!adev)
> > return -ENODEV;
> > diff --git a/drivers/media/pci/intel/ipu3/cio2-bridge.c b/drivers/media/pci/intel/ipu3/cio2-bridge.c
> > index 4657e99df033..59a36f922675 100644
> > --- a/drivers/media/pci/intel/ipu3/cio2-bridge.c
> > +++ b/drivers/media/pci/intel/ipu3/cio2-bridge.c
> > @@ -173,10 +173,8 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg,
> > int ret;
> >
> > for_each_acpi_dev_match(adev, cfg->hid, NULL, -1) {
> > - if (!adev->status.enabled) {
> > - acpi_dev_put(adev);
> > + if (!adev->status.enabled)
> > continue;
> > - }
> >
> > if (bridge->n_sensors >= CIO2_NUM_PORTS) {
> > acpi_dev_put(adev);
> > @@ -185,7 +183,6 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg,
> > }
> >
> > sensor = &bridge->sensors[bridge->n_sensors];
> > - sensor->adev = adev;
> > strscpy(sensor->name, cfg->hid, sizeof(sensor->name));
> >
> > ret = cio2_bridge_read_acpi_buffer(adev, "SSDB",
> > @@ -215,6 +212,7 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg,
> > goto err_free_swnodes;
> > }
> >
> > + sensor->adev = acpi_dev_get(adev);
> > adev->fwnode.secondary = fwnode;
> >
> > dev_info(&cio2->dev, "Found supported sensor %s\n",
> > diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> > index 1ae993fee4a5..b9d434a93632 100644
> > --- a/include/acpi/acpi_bus.h
> > +++ b/include/acpi/acpi_bus.h
> > @@ -707,11 +707,6 @@ acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv);
> > * @hrv: Hardware Revision of the device, pass -1 to not check _HRV
> > *
> > * The caller is responsible for invoking acpi_dev_put() on the returned device.
> > - *
> > - * FIXME: Due to above requirement there is a window that may invalidate @adev
> > - * and next iteration will use a dangling pointer, e.g. in the case of a
> > - * hotplug event. That said, the caller should ensure that this will never
> > - * happen.
> > */
> > #define for_each_acpi_dev_match(adev, hid, uid, hrv) \
> > for (adev = acpi_dev_get_first_match_dev(hid, uid, hrv); \