On 18 April 2017 at 18:01, Catalin Marinas <catalin.marinas@xxxxxxx> wrote: > On Thu, Apr 13, 2017 at 08:33:52PM +0800, dongbo (E) wrote: >> From: Dong Bo <dongbo4@xxxxxxxxxx> >> >> In load_elf_binary(), once the READ_IMPLIES_EXEC flag is set, >> the flag is propagated to its child processes, even the elf >> files are marked as not requiring executable stack. It may >> cause superfluous operations on some arch, e.g. >> __sync_icache_dcache on aarch64 due to a PROT_READ mmap is >> also marked as PROT_EXEC. > That's affecting most architectures with a risk of ABI breakage. We > could do it on arm64 only, though I'm not yet clear on the ABI > implications (at a first look, there shouldn't be any). Is there a reason why it isn't just straightforwardly a bug (which we could fix) to make READ_IMPLIES_EXEC propagate to child processes? AFAICT this should be per-process: just because init happens not to have been (re)compiled to permit non-executable stacks doesn't mean every process on the system needs to have an executable stack. Behaviour shouldn't be variable across architectures either, I would hope. thanks -- PMM
