From: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
[ Upstream commit e3fa4b747f085d2cda09bba0533b86fa76038635 ]
When channel->device_obj is non-NULL, vmbus_onoffer_rescind() could
invoke put_device(), that will eventually release the device and free
the channel object (cf. vmbus_device_release()). However, a pointer
to the object is dereferenced again later to load the primary_channel.
The use-after-free can be avoided by noticing that this load/check is
redundant if device_obj is non-NULL: primary_channel must be NULL if
device_obj is non-NULL, cf. vmbus_add_channel_work().
Fixes: 54a66265d6754b ("Drivers: hv: vmbus: Fix rescind handling")
Reported-by: Juan Vazquez <juvazq@xxxxxxxxxxxxx>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20201209070827.29335-5-parri.andrea@xxxxxxxxx
Signed-off-by: Wei Liu <wei.liu@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/hv/channel_mgmt.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 7920b0d7e35a7..ac9617671757c 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -1001,8 +1001,7 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
vmbus_device_unregister(channel->device_obj);
put_device(dev);
}
- }
- if (channel->primary_channel != NULL) {
+ } else if (channel->primary_channel != NULL) {
/*
* Sub-channel is being rescinded. Following is the channel
* close sequence when initiated from the driveri (refer to
--
2.27.0
