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[4.14,059/176] Drivers: hv: vmbus: Avoid use-after-free in vmbus_onoffer_rescind()

Message ID 20210301161023.880481531@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg KH March 1, 2021, 4:12 p.m. UTC 
From: Andrea Parri (Microsoft) <parri.andrea@gmail.com>

[ 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@microsoft.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20201209070827.29335-5-parri.andrea@gmail.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hv/channel_mgmt.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 5bf633c15cd4b..3891d3c2cc002 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -989,8 +989,7 @@  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 		 * Sub-channel is being rescinded.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