On 12/22/2014 12:52 PM, Andrey Ryabinin wrote: > 2014-12-22 18:51 GMT+03:00 Eric W. Biederman <ebiederm@xxxxxxxxxxxx>: >> These two instructions: >>>> 11: 4d 85 ff test %r15,%r15 >>>> 14: 0f 84 de 01 00 00 je 0x1f8 >> >> Should prevent a NULL %r15 value from ever reaching the trapping >> instruction. > > If they were executed, then yes. But I think there was jump from somewhere > to the instructions below those two. There is indeed a jump direct to that point, which avoids the %r15 check. >> What other horrible things does KASAN do to the machine code? >> > > kasan insert something like following before any memory access: > > s8 *shadow_addr = (add >> 3) + shadow_offset; > > if (unlikely(*shadow_addr)) > if (unlikely(addr & 7 >= *shadow_addr)) > report_bug(addr); > > > I suspect that Sasha is using kasan along with ubsan. > In that case generated code much more horrid. It's not *that* bad :) Thanks, Sasha -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
