From: Jason Gunthorpe jgg@nvidia.com
[ Upstream commit 0cb42c0265837fafa2b4f302c8a7fed2631d7869 ]
ib_unregister_device_queued() can only be used by drivers using the new dealloc_device callback flow, and it has a safety WARN_ON to ensure drivers are using it properly.
However, if unregister and register are raced there is a special destruction path that maintains the uniform error handling semantic of 'caller does ib_dealloc_device() on failure'. This requires disabling the dealloc_device callback which triggers the WARN_ON.
Instead of using NULL to disable the callback use a special function pointer so the WARN_ON does not trigger.
Fixes: d0899892edd0 ("RDMA/device: Provide APIs from the core code to help unregistration") Link: https://lore.kernel.org/r/0-v1-a36d512e0a99+762-syz_dealloc_driver_jgg@nvidi... Reported-by: syzbot+4088ed905e4ae2b0e13b@syzkaller.appspotmail.com Suggested-by: Hillf Danton hdanton@sina.com Reviewed-by: Leon Romanovsky leonro@mellanox.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/infiniband/core/device.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c index d0b3d35ad3e43..0fe3c3eb3dfd1 100644 --- a/drivers/infiniband/core/device.c +++ b/drivers/infiniband/core/device.c @@ -1327,6 +1327,10 @@ static int enable_device_and_get(struct ib_device *device) return ret; }
+static void prevent_dealloc_device(struct ib_device *ib_dev) +{ +} + /** * ib_register_device - Register an IB device with IB core * @device: Device to register @@ -1396,11 +1400,11 @@ int ib_register_device(struct ib_device *device, const char *name) * possibility for a parallel unregistration along with this * error flow. Since we have a refcount here we know any * parallel flow is stopped in disable_device and will see the - * NULL pointers, causing the responsibility to + * special dealloc_driver pointer, causing the responsibility to * ib_dealloc_device() to revert back to this thread. */ dealloc_fn = device->ops.dealloc_driver; - device->ops.dealloc_driver = NULL; + device->ops.dealloc_driver = prevent_dealloc_device; ib_device_put(device); __ib_unregister_device(device); device->ops.dealloc_driver = dealloc_fn; @@ -1448,7 +1452,8 @@ static void __ib_unregister_device(struct ib_device *ib_dev) * Drivers using the new flow may not call ib_dealloc_device except * in error unwind prior to registration success. */ - if (ib_dev->ops.dealloc_driver) { + if (ib_dev->ops.dealloc_driver && + ib_dev->ops.dealloc_driver != prevent_dealloc_device) { WARN_ON(kref_read(&ib_dev->dev.kobj.kref) <= 1); ib_dealloc_device(ib_dev); }