Fix port_paremeter_get function blindly subtracts 8 from a reply
size without checking that the size is at lest 8 bytes. This can
casue a large buffer to be copied since the size is unsigned.
Add a WARN_ON, and also add min and max conditions to the size
of the data that is copied.
Signed-off-by: Michael Zoran <mzo...@crowfest.net>
---
.../vc04_services/bcm2835-camera/mmal-vchiq.c | 27 +++++++++++-----------
1 file changed, 14 insertions(+), 13 deletions(-)
diff --git a/drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c
b/drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c
index 4f4499dfe0c3..a8768358c557 100644
--- a/drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c
+++ b/drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c
@@ -1450,23 +1450,24 @@ static int port_parameter_get(struct
vchiq_mmal_instance *instance,
* port_parameter_get_reply.size includes the header,
* whilst *value_size doesn't.
*/
- reply_size = rmsg->u.port_parameter_get_reply.size - (2 * sizeof(u32));
- if (ret || (reply_size > *value_size)) {
- /* Copy only as much as we have space for
- * but report true size of parameter
- */
- memcpy(value, &rmsg->u.port_parameter_get_reply.value,
- *value_size);
- } else
- memcpy(value, &rmsg->u.port_parameter_get_reply.value,
- reply_size);
+ if (WARN_ON(rmsg->u.port_parameter_get_reply.size < 8))
+ reply_size = 0;
+ else
+ reply_size = rmsg->u.port_parameter_get_reply.size - 8;
/*
- * Return amount of data copied if big enough,
- * or wanted if not big enough.
+ * The API for port_parameter_get() requires that the
+ * filled length is returned, or if insufficient space
+ * that the required space is returned.
+ *
+ * See Commit: 95452744c5ebcaa0f5d4eaff7313b2b4cd51bd9f
+ * https://github.com/raspberrypi/linux
*/
- *value_size = reply_size;
+
+ memcpy(value, &rmsg->u.port_parameter_get_reply.value,
+ min(*value_size, reply_size));
+ *value_size = max(reply_size, *value_size);
pr_debug("%s:result:%d component:0x%x port:%d parameter:%d\n", __func__,
ret, port->component->handle, port->handle, parameter_id);
--
2.11.0
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