| Message ID | 1418302280-14794-5-git-send-email-peter@lekensteyn.nl (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Jiri Kosina |
| Headers | show |
On Dec 11 2014 or thereabouts, Peter Wu wrote: > Balance a hid_device_io_start() call with hid_device_io_stop() in the > error path. This avoids processing of HID reports when the probe fails > which possibly leads to invalid memory access in hid_device_probe() as > report_enum->report_id_hash might already be freed via > hid_close_report(). Well spotted too! > > hid_set_drvdata() is called before wtp_allocate, be consistent and clear > drvdata too on the error path of wtp_allocate. This is not strictly speaking required. We will have a dangling value in hdev->private_data, but this should be overwritten before the next use. Anyway, it makes sense to clean up after a failure, so the patch is Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> Cheers, Benjamin > > Signed-off-by: Peter Wu <peter@lekensteyn.nl> > --- > Hi Andrew, > > There are few users of hid_device_io_start/stop, this is the first one > to get start/stop out of sync. Should the comment of > hid_device_io_start() be updated to ensure that hid_device_io_stop() > gets called before probe() returns? Or should the hid-core be changed to > handle this out-of-sync issue: > > if (ret) { > if (hdev->io_started)) > down(&hdev->driver_input_lock); > hid_close_report(hdev); > hdev->driver = NULL; > } > > Is my observation correct or not that HID reports can arrive during > hid_close_report() when io_started == true? > > Kind regards, > Peter > --- > drivers/hid/hid-logitech-hidpp.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c > index 4292cc3..2f420c0 100644 > --- a/drivers/hid/hid-logitech-hidpp.c > +++ b/drivers/hid/hid-logitech-hidpp.c > @@ -1121,7 +1121,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) > if (hidpp->quirks & HIDPP_QUIRK_CLASS_WTP) { > ret = wtp_allocate(hdev, id); > if (ret) > - return ret; > + goto wtp_allocate_fail; > } > > INIT_WORK(&hidpp->work, delayed_work_cb); > @@ -1141,6 +1141,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) > if (id->group != HID_GROUP_LOGITECH_DJ_DEVICE) { > if (!connected) { > hid_err(hdev, "Device not connected"); > + hid_device_io_stop(hdev); > goto hid_parse_fail; > } > > @@ -1186,6 +1187,7 @@ hid_hw_start_fail: > hid_parse_fail: > cancel_work_sync(&hidpp->work); > mutex_destroy(&hidpp->send_mutex); > +wtp_allocate_fail: > hid_set_drvdata(hdev, NULL); > return ret; > } > -- > 2.1.3 > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu Dec 11 2014 at 7:31:43 AM Benjamin Tissoires <benjamin.tissoires@redhat.com> wrote: > > On Dec 11 2014 or thereabouts, Peter Wu wrote: > > Balance a hid_device_io_start() call with hid_device_io_stop() in the > > error path. This avoids processing of HID reports when the probe fails > > which possibly leads to invalid memory access in hid_device_probe() as > > report_enum->report_id_hash might already be freed via > > hid_close_report(). > > Well spotted too! > > > > > hid_set_drvdata() is called before wtp_allocate, be consistent and clear > > drvdata too on the error path of wtp_allocate. > > This is not strictly speaking required. We will have a dangling value in > hdev->private_data, but this should be overwritten before the next use. > > Anyway, it makes sense to clean up after a failure, so the patch is > Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> > > Cheers, > Benjamin > > > > > Signed-off-by: Peter Wu <peter@lekensteyn.nl> > > --- > > Hi Andrew, > > > > There are few users of hid_device_io_start/stop, this is the first one > > to get start/stop out of sync. Should the comment of > > hid_device_io_start() be updated to ensure that hid_device_io_stop() > > gets called before probe() returns? Or should the hid-core be changed to > > handle this out-of-sync issue: I do not have a strong opinion on this, and will defer to others. The reason I needed to communicate during probe() was to have the driver probe the actual device for details. In this use case, I would be okay to disable IO at the end of probe() and have it become reenabled via the normal (default) methods. -andrew > > > > if (ret) { > > if (hdev->io_started)) > > down(&hdev->driver_input_lock); > > hid_close_report(hdev); > > hdev->driver = NULL; > > } > > > > Is my observation correct or not that HID reports can arrive during > > hid_close_report() when io_started == true? > > > > Kind regards, > > Peter > > --- > > drivers/hid/hid-logitech-hidpp.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c > > index 4292cc3..2f420c0 100644 > > --- a/drivers/hid/hid-logitech-hidpp.c > > +++ b/drivers/hid/hid-logitech-hidpp.c > > @@ -1121,7 +1121,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) > > if (hidpp->quirks & HIDPP_QUIRK_CLASS_WTP) { > > ret = wtp_allocate(hdev, id); > > if (ret) > > - return ret; > > + goto wtp_allocate_fail; > > } > > > > INIT_WORK(&hidpp->work, delayed_work_cb); > > @@ -1141,6 +1141,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) > > if (id->group != HID_GROUP_LOGITECH_DJ_DEVICE) { > > if (!connected) { > > hid_err(hdev, "Device not connected"); > > + hid_device_io_stop(hdev); > > goto hid_parse_fail; > > } > > > > @@ -1186,6 +1187,7 @@ hid_hw_start_fail: > > hid_parse_fail: > > cancel_work_sync(&hidpp->work); > > mutex_destroy(&hidpp->send_mutex); > > +wtp_allocate_fail: > > hid_set_drvdata(hdev, NULL); > > return ret; > > } > > -- > > 2.1.3 > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-input" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thursday 11 December 2014 09:37:06 Andrew de los Reyes wrote: > On Thu Dec 11 2014 at 7:31:43 AM Benjamin Tissoires > <benjamin.tissoires@redhat.com> wrote: > > > > On Dec 11 2014 or thereabouts, Peter Wu wrote: > > > Balance a hid_device_io_start() call with hid_device_io_stop() in the > > > error path. This avoids processing of HID reports when the probe fails > > > which possibly leads to invalid memory access in hid_device_probe() as > > > report_enum->report_id_hash might already be freed via > > > hid_close_report(). > > > > Well spotted too! > > > > > > > > hid_set_drvdata() is called before wtp_allocate, be consistent and clear > > > drvdata too on the error path of wtp_allocate. > > > > This is not strictly speaking required. We will have a dangling value in > > hdev->private_data, but this should be overwritten before the next use. > > > > Anyway, it makes sense to clean up after a failure, so the patch is > > Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> > > > > Cheers, > > Benjamin > > > > > > > > Signed-off-by: Peter Wu <peter@lekensteyn.nl> > > > --- > > > Hi Andrew, > > > > > > There are few users of hid_device_io_start/stop, this is the first one > > > to get start/stop out of sync. Should the comment of > > > hid_device_io_start() be updated to ensure that hid_device_io_stop() > > > gets called before probe() returns? Or should the hid-core be changed to > > > handle this out-of-sync issue: > > I do not have a strong opinion on this, and will defer to others. The > reason I needed to communicate during probe() was to have the driver > probe the actual device for details. In this use case, I would be okay > to disable IO at the end of probe() and have it become reenabled via > the normal (default) methods. > > -andrew Keeping the reports enabled when the probe succeeds is fine, I am referring to the error path. If the probe fails, then reports should never be accepted or a corruption may occur (if I see it correctly). Is this analysis correct? hid_device_probe() hid_device_io_start() return FAILURE hid_close_report(device) report_enum = device ->report_enum[i] hid_free_report(report_enum ->report_id_hash[j]) <-- NOTE: freed ... interrupt occurs ... hid_input_report() hid_get_report() report = report_enum->report_id_hash[n]; ^ NOTE: use-after-free return report if not NULL hdrv->raw_event(report) <--- BOOM? kfree(device->rdesc) device->driver = NULL Kind regards, Peter > > > > > > if (ret) { > > > if (hdev->io_started)) > > > down(&hdev->driver_input_lock); > > > hid_close_report(hdev); > > > hdev->driver = NULL; > > > } > > > > > > Is my observation correct or not that HID reports can arrive during > > > hid_close_report() when io_started == true? > > > > > > Kind regards, > > > Peter > > > --- > > > drivers/hid/hid-logitech-hidpp.c | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c > > > index 4292cc3..2f420c0 100644 > > > --- a/drivers/hid/hid-logitech-hidpp.c > > > +++ b/drivers/hid/hid-logitech-hidpp.c > > > @@ -1121,7 +1121,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) > > > if (hidpp->quirks & HIDPP_QUIRK_CLASS_WTP) { > > > ret = wtp_allocate(hdev, id); > > > if (ret) > > > - return ret; > > > + goto wtp_allocate_fail; > > > } > > > > > > INIT_WORK(&hidpp->work, delayed_work_cb); > > > @@ -1141,6 +1141,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) > > > if (id->group != HID_GROUP_LOGITECH_DJ_DEVICE) { > > > if (!connected) { > > > hid_err(hdev, "Device not connected"); > > > + hid_device_io_stop(hdev); > > > goto hid_parse_fail; > > > } > > > > > > @@ -1186,6 +1187,7 @@ hid_hw_start_fail: > > > hid_parse_fail: > > > cancel_work_sync(&hidpp->work); > > > mutex_destroy(&hidpp->send_mutex); > > > +wtp_allocate_fail: > > > hid_set_drvdata(hdev, NULL); > > > return ret; > > > } > > > -- > > > 2.1.3 > > > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
I would think you'd need to call hid_device_io_stop in probe before returning just to make sure the hid->driver_input_lock is in the right state. You may be able to consult hid->io_started in the probe thread after calling probe, and do the appropriate cleanup if probe returned error. IMHO I like to keep things like lock/unlock in pairs near each other, so it seems preferable to require that drivers handle calling hid_device_io_stop themselves if probe will fail. I don't know in general what the Linux stance is, tho. -andrew On Thu, Dec 11, 2014 at 9:53 AM, Peter Wu <peter@lekensteyn.nl> wrote: > On Thursday 11 December 2014 09:37:06 Andrew de los Reyes wrote: >> On Thu Dec 11 2014 at 7:31:43 AM Benjamin Tissoires >> <benjamin.tissoires@redhat.com> wrote: >> > >> > On Dec 11 2014 or thereabouts, Peter Wu wrote: >> > > Balance a hid_device_io_start() call with hid_device_io_stop() in the >> > > error path. This avoids processing of HID reports when the probe fails >> > > which possibly leads to invalid memory access in hid_device_probe() as >> > > report_enum->report_id_hash might already be freed via >> > > hid_close_report(). >> > >> > Well spotted too! >> > >> > > >> > > hid_set_drvdata() is called before wtp_allocate, be consistent and clear >> > > drvdata too on the error path of wtp_allocate. >> > >> > This is not strictly speaking required. We will have a dangling value in >> > hdev->private_data, but this should be overwritten before the next use. >> > >> > Anyway, it makes sense to clean up after a failure, so the patch is >> > Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> >> > >> > Cheers, >> > Benjamin >> > >> > > >> > > Signed-off-by: Peter Wu <peter@lekensteyn.nl> >> > > --- >> > > Hi Andrew, >> > > >> > > There are few users of hid_device_io_start/stop, this is the first one >> > > to get start/stop out of sync. Should the comment of >> > > hid_device_io_start() be updated to ensure that hid_device_io_stop() >> > > gets called before probe() returns? Or should the hid-core be changed to >> > > handle this out-of-sync issue: >> >> I do not have a strong opinion on this, and will defer to others. The >> reason I needed to communicate during probe() was to have the driver >> probe the actual device for details. In this use case, I would be okay >> to disable IO at the end of probe() and have it become reenabled via >> the normal (default) methods. >> >> -andrew > > Keeping the reports enabled when the probe succeeds is fine, I am > referring to the error path. If the probe fails, then reports should > never be accepted or a corruption may occur (if I see it correctly). > > Is this analysis correct? > > hid_device_probe() > hid_device_io_start() > return FAILURE > hid_close_report(device) > report_enum = device > ->report_enum[i] > hid_free_report(report_enum > ->report_id_hash[j]) <-- NOTE: freed > ... interrupt occurs ... > hid_input_report() > hid_get_report() > report = report_enum->report_id_hash[n]; > ^ NOTE: use-after-free > return report if not NULL > hdrv->raw_event(report) <--- BOOM? > kfree(device->rdesc) > device->driver = NULL > > Kind regards, > Peter > >> > > >> > > if (ret) { >> > > if (hdev->io_started)) >> > > down(&hdev->driver_input_lock); >> > > hid_close_report(hdev); >> > > hdev->driver = NULL; >> > > } >> > > >> > > Is my observation correct or not that HID reports can arrive during >> > > hid_close_report() when io_started == true? >> > > >> > > Kind regards, >> > > Peter >> > > --- >> > > drivers/hid/hid-logitech-hidpp.c | 4 +++- >> > > 1 file changed, 3 insertions(+), 1 deletion(-) >> > > >> > > diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c >> > > index 4292cc3..2f420c0 100644 >> > > --- a/drivers/hid/hid-logitech-hidpp.c >> > > +++ b/drivers/hid/hid-logitech-hidpp.c >> > > @@ -1121,7 +1121,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) >> > > if (hidpp->quirks & HIDPP_QUIRK_CLASS_WTP) { >> > > ret = wtp_allocate(hdev, id); >> > > if (ret) >> > > - return ret; >> > > + goto wtp_allocate_fail; >> > > } >> > > >> > > INIT_WORK(&hidpp->work, delayed_work_cb); >> > > @@ -1141,6 +1141,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) >> > > if (id->group != HID_GROUP_LOGITECH_DJ_DEVICE) { >> > > if (!connected) { >> > > hid_err(hdev, "Device not connected"); >> > > + hid_device_io_stop(hdev); >> > > goto hid_parse_fail; >> > > } >> > > >> > > @@ -1186,6 +1187,7 @@ hid_hw_start_fail: >> > > hid_parse_fail: >> > > cancel_work_sync(&hidpp->work); >> > > mutex_destroy(&hidpp->send_mutex); >> > > +wtp_allocate_fail: >> > > hid_set_drvdata(hdev, NULL); >> > > return ret; >> > > } >> > > -- >> > > 2.1.3 >> > > > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c index 4292cc3..2f420c0 100644 --- a/drivers/hid/hid-logitech-hidpp.c +++ b/drivers/hid/hid-logitech-hidpp.c @@ -1121,7 +1121,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) if (hidpp->quirks & HIDPP_QUIRK_CLASS_WTP) { ret = wtp_allocate(hdev, id); if (ret) - return ret; + goto wtp_allocate_fail; } INIT_WORK(&hidpp->work, delayed_work_cb); @@ -1141,6 +1141,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) if (id->group != HID_GROUP_LOGITECH_DJ_DEVICE) { if (!connected) { hid_err(hdev, "Device not connected"); + hid_device_io_stop(hdev); goto hid_parse_fail; } @@ -1186,6 +1187,7 @@ hid_hw_start_fail: hid_parse_fail: cancel_work_sync(&hidpp->work); mutex_destroy(&hidpp->send_mutex); +wtp_allocate_fail: hid_set_drvdata(hdev, NULL); return ret; }
Balance a hid_device_io_start() call with hid_device_io_stop() in the error path. This avoids processing of HID reports when the probe fails which possibly leads to invalid memory access in hid_device_probe() as report_enum->report_id_hash might already be freed via hid_close_report(). hid_set_drvdata() is called before wtp_allocate, be consistent and clear drvdata too on the error path of wtp_allocate. Signed-off-by: Peter Wu <peter@lekensteyn.nl> --- Hi Andrew, There are few users of hid_device_io_start/stop, this is the first one to get start/stop out of sync. Should the comment of hid_device_io_start() be updated to ensure that hid_device_io_stop() gets called before probe() returns? Or should the hid-core be changed to handle this out-of-sync issue: if (ret) { if (hdev->io_started)) down(&hdev->driver_input_lock); hid_close_report(hdev); hdev->driver = NULL; } Is my observation correct or not that HID reports can arrive during hid_close_report() when io_started == true? Kind regards, Peter --- drivers/hid/hid-logitech-hidpp.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)