On Thu, Jul 20, 2023 at 02:12:13PM +0000, Konstantin Belousov wrote: > The branch main has been updated by kib: > > URL: > https://cgit.FreeBSD.org/src/commit/?id=21e45c30c35c9aa732073f725924caf581c93460 > > commit 21e45c30c35c9aa732073f725924caf581c93460 > Author: Konstantin Belousov <k...@freebsd.org> > AuthorDate: 2023-07-19 11:05:32 +0000 > Commit: Konstantin Belousov <k...@freebsd.org> > CommitDate: 2023-07-20 14:11:42 +0000 > > mmap(MAP_STACK): on stack grow, use original protection > > If mprotect(2) changed protection in the bottom of the currently grown > stack region, currently the changed protection would be used for the > stack grow on next fault. This is arguably unexpected. > > Store the original protection for the entry at mmap(2) time in the > offset member of the gap vm_map_entry, and use it for protection of the > grown stack region.
It occured to me to wonder how this interacts with __enable_execute_stack(). I think it's ok so long as the compiler always emits __enable_execute_stack() for each trampoline and doesn't depend on extentions to the stack being executable from the first trampoline creation, but I don't know where to look to verify that's the case. -- Brooks
