locks use-after-free stable request

Referencing upstream fixes commit dcf23ac3e846ca0cf626c155a0e3fcbbcf4fae8a ("locks: reinstate locks_delete_block optimization") and commit 6d390e4b5d48ec03bb87e63cf0a2bff5f4e116da ("locks: fix a potential use-after-free problem when wakeup a waiter") and possibly address CVE-2019-19769.

Please apply to all relevant stable trees including 5.4, 4.19 and below. Confirmed they apply cleanly to 5.4 and 4.19.

Signed-off-by: Mark Salyzyn salyzyn@android.com

Cc: stable@vger.kernel.org

Cc: linux-kernel@vger.kernel.org

Cc: kernel-team@android.com