On Mon, 30 Aug 2021 at 16:47, Eric Blake <ebl...@redhat.com> wrote: > > On Sun, Aug 29, 2021 at 10:09:19PM +0100, Peter Maydell wrote: > > Of the various KVM_* ioctls we use via these functions, do > > any actually have values that would result in invalid sign > > extension here ? That is, is this fixing an existing bug, or is > > it merely avoiding a potential future bug? > > My question as well. If there is such a bug, calling it out in the > commit message is essential; if the bug is just theoretical, > mentioning that is still useful.
I found this glibc bug from 2012, filed by some random guy named Linus Torvalds, and still open: https://sourceware.org/bugzilla/show_bug.cgi?id=14362 where among other things he claims # As noted, this does not actually cause problems on Linux, because # unlike FreeBSD, Linux knows what the f*ck it is doing, and just # ignores the upper bits exactly because of possible sign confusion. Whether that's still true a decade later I have no idea :-) -- PMM
