In the Linux kernel, the following vulnerability has been resolved: listmount: don't call path_put() under namespace semaphore Massage listmount() and make sure we don't call path_put() under the namespace semaphore. If we put the last reference we're fscked.
https://git.kernel.org/stable/c/c1f86d0ac322c7e77f6f8dbd216c65d39358ffc0
https://git.kernel.org/stable/c/9c80da26fda2fdcaac7f92b5908875b3108830ff
https://git.kernel.org/stable/c/659874b7ee4976ad9ce476e07fd36bc67b3537f1