On Tue, Nov 24, 2020 at 11:19:33AM +0100, Borislav Petkov wrote: > In any case, at least the case where I give it > > 0x48 0xcf 0x48 0x83 > > and say that buf size is 4, should return an error because the second > insn is incomplete. So I need to go look at that now.
Ok, got it: ./arch/x86/tools/insn_sanity: Success: decoded and checked 10000 random instructions with 0 errors (seed:0x826fdf9c) insn buffer: 0x48 0xcf 0x48 0x83 0x90 0x90 0x90 0x90 0x90 0x90 0x90 0x90 0x90 0x90 0x90 supplied buf size: 15, ret 0 supplied buf size: 2, ret 0 supplied buf size: 3, ret 0 supplied buf size: 4, ret 0 supplied buf size: 1, ret -22 the current decoder simply decodes the *first* insn in the buffer it encounters and that's it. When you give it a buffer of size smaller than the first instruction: supplied buf size: 1, ret -22 while the first insn is 2 bytes long: 0x48 0xcf (IRETQ) then it signals an error. Andy, does that work for your use cases? -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette