> On Thu, Apr 4, 2019 at 4:41 AM Reshetova, Elena > <elena.reshetova@xxxxxxxxx> wrote: > > What I still don't fully understand here (due to my little knowledge of > > compilers) and afraid of is that the asm code that alloca generates (see my version) > > and the alignment might differ on the different targets, etc. > > I guess it's possible, but for x86_64, since appears to be consistent. So, yes, I double checked this now with just printing all possible offsets I get for rsp from do_syscall_64, it is indeed 33 different offsets, so it is indeed more like 5 bits of entropy. We can increase it, if we want and people are ok with losing a bit more stack space. > > > If you tried it on yours, can you send me the asm code that it produced for you? > > Is it different from mine? > > You can compare compiler outputs here. Here's gcc vs clang for this code: > https://godbolt.org/z/WJSbN8 > You can adjust compiler versions, etc. Oh, this is handy! Thank you for the link! So, should I resend to lkml (with some cosmetic fixes) or how to proceed with this? I will also update the randomness bit info. Best Regards, Elena.
