[PATCH v2 2/3] firmware: qcom_scm: handle empty PAS resource table

[Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>]

The PAS resource-table query may successfully return a zero-sized
table. kmemdup() with a zero length returns ZERO_SIZE_PTR,
which is stored in rproc->table_ptr. The remoteproc core then
dereferences this invalid pointer while processing resources.

Treat a zero-sized result as an absent resource table and return
NULL after releasing the TrustZone memory buffer. This allows the
remoteproc core to skip resource-table processing.

Fixes: 8b9d2050cfa0 ("firmware: qcom_scm: Add qcom_scm_pas_get_rsc_table() to get resource table")
Signed-off-by: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>
---
Changes in v2:
 - New change.

 drivers/firmware/qcom/qcom_scm.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index df20773dd754..b5959f833dd7 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -823,6 +823,14 @@ static void *qcom_scm_pas_get_rsc_table(struct device *dev,
 		goto free_input_rt;
 	}
 
+	*output_rt_size = size;
+
+	/* A zero-sized table means that TrustZone has no resource table. */
+	if (!size) {
+		tbl_ptr = NULL;
+		goto free_output_rt;
+	}
+
 	tbl_ptr = kmemdup(output_rt_tzm, size, GFP_KERNEL);
 	if (!tbl_ptr) {
 		qcom_tzmem_free(output_rt_tzm);
@@ -830,7 +838,7 @@ static void *qcom_scm_pas_get_rsc_table(struct device *dev,
 		goto free_input_rt;
 	}
 
-	*output_rt_size = size;
+free_output_rt:
 	qcom_tzmem_free(output_rt_tzm);
 
 free_input_rt:
-- 
2.55.0