Re: [PATCH 1/2] memfd: Fix COW issue on MAP_PRIVATE and F_SEAL_FUTURE_WRITE mappings

On Thu, 7 Nov 2019 14:53:54 -0500 "Joel Fernandes (Google)" joel@joelfernandes.org wrote:

F_SEAL_FUTURE_WRITE has unexpected behavior when used with MAP_PRIVATE: A private mapping created after the memfd file that gets sealed with F_SEAL_FUTURE_WRITE loses the copy-on-write at fork behavior, meaning children and parent share the same memory, even though the mapping is private.

That sounds fairly serious. Should this be backported into -stable kernels?