On Wed, 2 Dec 2020 11:04:41 -0800
Kees Cook <keesc...@chromium.org> wrote:
> On Wed, Dec 02, 2020 at 05:51:16PM +0900, Masami Hiramatsu wrote:
> > Since the insn.prefixes.nbytes can be bigger than the size of
> > insn.prefixes.bytes[] when a same prefix is repeated, we have to
> > check whether the insn.prefixes.bytes[i] != 0 and i < 4 instead
> > of insn.prefixes.nbytes.
> >
> > Fixes: 2b1444983508 ("uprobes, mm, x86: Add the ability to install and
> > remove uprobes breakpoints")
> > Cc: sta...@vger.kernel.org
> > Reported-by: Kees Cook <keesc...@chromium.org>
>
> This should probably be:
>
> Reported-by: syzbot+9b64b619f10f19d19...@syzkaller.appspotmail.com
> Debugged-by: Kees Cook <keesc...@chromium.org>
OK, let me fix it.
Thank you,
>
> > Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
> > ---
> > arch/x86/kernel/uprobes.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
> > index 3fdaa042823d..bb3ea3705b99 100644
> > --- a/arch/x86/kernel/uprobes.c
> > +++ b/arch/x86/kernel/uprobes.c
> > @@ -257,7 +257,7 @@ static bool is_prefix_bad(struct insn *insn)
> > {
> > int i;
> >
> > - for (i = 0; i < insn->prefixes.nbytes; i++) {
> > + for (i = 0; insn->prefixes.bytes[i] && i < 4; i++) {
> > insn_attr_t attr;
> >
> > attr = inat_get_opcode_attribute(insn->prefixes.bytes[i]);
> > @@ -746,7 +746,7 @@ static int branch_setup_xol_ops(struct arch_uprobe
> > *auprobe, struct insn *insn)
> > * Intel and AMD behavior differ in 64-bit mode: Intel ignores 66
> > prefix.
> > * No one uses these insns, reject any branch insns with such prefix.
> > */
> > - for (i = 0; i < insn->prefixes.nbytes; i++) {
> > + for (i = 0; insn->prefixes.bytes[i] && i < 4; i++) {
> > if (insn->prefixes.bytes[i] == 0x66)
> > return -ENOTSUPP;
> > }
> >
>
>
> --
> Kees Cook
--
Masami Hiramatsu <mhira...@kernel.org>
