[PATCH AUTOSEL 4.20 171/304] switchtec: Fix SWITCHTEC_IOCTL_EVENT_IDX_ALL flags overwrite

[Sasha Levin]

From: Joey Zhang <joey.zhang@xxxxxxxxxxxxx>

[ Upstream commit e4a7dca5de625018b29417ecc39dc5037d9a5a36 ]

In the ioctl_event_ctl() SWITCHTEC_IOCTL_EVENT_IDX_ALL case, we call
event_ctl() several times with the same "ctl" struct.  Each call clobbers
ctl.flags, which leads to the problem that we may not actually enable or
disable all events as the user requested.

Preserve the event flag value with a temporary variable.

Fixes: 52eabba5bcdb ("switchtec: Add IOCTLs to the Switchtec driver")
Signed-off-by: Joey Zhang <joey.zhang@xxxxxxxxxxxxx>
Signed-off-by: Wesley Sheng <wesley.sheng@xxxxxxxxxxxxx>
[bhelgaas: changelog]
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/pci/switch/switchtec.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c
index 54a8b30dda38..37d0c15c9eeb 100644
--- a/drivers/pci/switch/switchtec.c
+++ b/drivers/pci/switch/switchtec.c
@@ -800,6 +800,7 @@ static int ioctl_event_ctl(struct switchtec_dev *stdev,
 {
 	int ret;
 	int nr_idxs;
+	unsigned int event_flags;
 	struct switchtec_ioctl_event_ctl ctl;
 
 	if (copy_from_user(&ctl, uctl, sizeof(ctl)))
@@ -821,7 +822,9 @@ static int ioctl_event_ctl(struct switchtec_dev *stdev,
 		else
 			return -EINVAL;
 
+		event_flags = ctl.flags;
 		for (ctl.index = 0; ctl.index < nr_idxs; ctl.index++) {
+			ctl.flags = event_flags;
 			ret = event_ctl(stdev, &ctl);
 			if (ret < 0)
 				return ret;
-- 
2.19.1