On Thu, Nov 07, 2019 at 09:06:14PM -0500, Joel Fernandes wrote: > On Thu, Nov 07, 2019 at 05:00:23PM -0800, Andrew Morton wrote: > > On Thu, 7 Nov 2019 14:53:54 -0500 "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx> 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? > > Yes, it should be. The F_SEAL_FUTURE_WRITE feature was introduced in v5.1 so > v5.3.x stable kernels would need a backport. I can submit a backport tomorrow > unless we are Ok with stable automatically picking it up (I believe the > stable folks "auto select" fixes which should detect this is a fix since I > have said it is a fix in the subject line). Never rely on "auto select" to pick up a patch for stable if you already know it should go to stable. Just mark it as such, or tell stable@vger after the fact. thanks, greg k-h
