[PATCH 14/14] drm/amd/display: Fix static analysis bug in validate_bksv

Bhawanpreet Lakha Bhawanpreet.Lakha at amd.com
Thu Nov 7 15:56:28 UTC 2019


[Why]
static analysis throws the error below

Out-of-bounds read (OVERRUN)
Overrunning array of 5 bytes at byte offset 7 by dereferencing pointer
(uint64_t *)hdcp->auth.msg.hdcp1.bksv.

var n is going to contain  r0p and bcaps. if they are non-zero the count
will be wrong

How]
Use memcpy instead to avoid this.

Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha at amd.com>
---
 drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c
index 4d11041a8c6f..04845e43df15 100644
--- a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c
+++ b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c
@@ -27,9 +27,11 @@
 
 static inline enum mod_hdcp_status validate_bksv(struct mod_hdcp *hdcp)
 {
-	uint64_t n = *(uint64_t *)hdcp->auth.msg.hdcp1.bksv;
+	uint64_t n = 0;
 	uint8_t count = 0;
 
+	memcpy(&n, hdcp->auth.msg.hdcp1.bksv, sizeof(uint64_t));
+
 	while (n) {
 		count++;
 		n &= (n - 1);
-- 
2.17.1



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