On Fri, Apr 8, 2016 at 12:13 AM, Ingo Molnar <mi...@kernel.org> wrote: > > * Andy Lutomirski <l...@kernel.org> wrote: > >> ARCH_GET_FS and ARCH_GET_GS attempted to figure out the fsbase and >> gsbase respectively from saved thread state. This was wrong: fsbase >> and gsbase live in registers while a thread is running, not in >> memory. > > So I'm wondering, the current code looks totally broken,what user-space code > can > possibly use this? I checked glibc and Wine, and neither of them does. Wine > uses > ARCH_SET_GS and glibc uses ARCH_SET_FS, but that's all - neither actually > tries to > use the ARCH_GET_* reading APIs. > > So for backporting purposes I'd be much happier about simply returning > -EINVAL or > -ENOSYS, and we could re-introduce this code in v4.7. >
Let's just not backport this one. There's no security issue here. If you like the rest of the series, can you remove the stable tag from this patch when you apply it? I think the old code was at least correct enough that if you did ARCH_GET_FS after ARCH_SET_FS with no funny business in between, it would work. --Andy -- Andy Lutomirski AMA Capital Management, LLC
