On Wed, Nov 2, 2022 at 1:51 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > On Wed, Nov 02, 2022 at 12:06:11PM +0100, Alexander Potapenko wrote: > > There is a case in exc_invalid_op handler that is executed outside the > > irqentry_enter()/irqentry_exit() region when an UD2 instruction is used > > to encode a call to __warn(). > > > > In that case the `struct pt_regs` passed to the interrupt handler is > > never unpoisoned by KMSAN (this is normally done in irqentry_enter()), > > which leads to false positives inside handle_bug(). > > > > Use kmsan_unpoison_entry_regs() to explicitly unpoison those registers > > before using them. > > As does poke_int3_handler(); does that need fixing up too? OTOH look > *very very* carefully at the contraints there. Fortunately poke_int3_handler() is a noinstr function, so KMSAN doesn't add any checks to it. It also does not pass regs to other instrumented functions, at least for now, so we're good. -- Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Straße, 33 80636 München Geschäftsführer: Paul Manicle, Liana Sebastian Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg
