[PATCH AUTOSEL 4.14 40/72] media: cec: silence shift wrapping warning in __cec_s_log_addrs()

Sasha Levin
2020-06-08T23:36:14Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit 3b5af3171e2d5a73ae6f04965ed653d039904eb6 ]

The log_addrs->log_addr_type[i] value is a u8 which is controlled by
the user and comes from the ioctl. If it's over 31 then that results in
undefined behavior (shift wrapping) and that leads to a Smatch static
checker warning. We already cap the value later so we can silence the
warning just by re-ordering the existing checks.

I think the UBSan checker will also catch this bug at runtime and
generate a warning. But otherwise the bug is harmless.

Fixes: 9881fe0ca187 ("[media] cec: add HDMI CEC framework (adapter)")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/media/cec/cec-adap.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/media/cec/cec-adap.c b/drivers/media/cec/cec-adap.c
index 0d7d687aeea0..061b7824f698 100644
--- a/drivers/media/cec/cec-adap.c
+++ b/drivers/media/cec/cec-adap.c
@@ -1624,6 +1624,10 @@ int __cec_s_log_addrs(struct cec_adapter *adap,
unsigned j;

log_addrs->log_addr[i] = CEC_LOG_ADDR_INVALID;
+ if (log_addrs->log_addr_type[i] > CEC_LOG_ADDR_TYPE_UNREGISTERED) {
+ dprintk(1, "unknown logical address type\n");
+ return -EINVAL;
+ }
if (type_mask & (1 << log_addrs->log_addr_type[i])) {
dprintk(1, "duplicate logical address type\n");
return -EINVAL;
@@ -1644,10 +1648,6 @@ int __cec_s_log_addrs(struct cec_adapter *adap,
dprintk(1, "invalid primary device type\n");
return -EINVAL;
}
- if (log_addrs->log_addr_type[i] > CEC_LOG_ADDR_TYPE_UNREGISTERED) {
- dprintk(1, "unknown logical address type\n");
- return -EINVAL;
- }
for (j = 0; j < feature_sz; j++) {
if ((features[j] & 0x80) == 0) {
if (op_is_dev_features)
--
2.25.1