Re: [PATCH] ACPICA: Fix operand resolution

[Amadeusz Sławiński]

On 12/8/2022 12:55 PM, Rafael J. Wysocki wrote:
> On Thu, Dec 8, 2022 at 12:51 PM Amadeusz Sławiński
> <amadeuszx.slawinski@xxxxxxxxxxxxxxx> wrote:
> > In our tests we get UBSAN warning coming from ACPI parser. This is
> > caused by trying to resolve operands when there is none.
> >
> > [    0.000000] Linux version 5.15.0-rc3chromeavsrel1.0.184+ (root@...) (gcc (Ubuntu 10.3.0-1ubuntu1~20.04) 10.3.0, GNU ld (GNU Binutils for Ubuntu) 2.34) #1 SMP PREEMPT Sat Oct 16 00:08:27 UTC 2021
> > ...
> > [ 14.719508] ================================================================================
> > [ 14.719551] UBSAN: array-index-out-of-bounds in /.../linux/drivers/acpi/acpica/dswexec.c:401:12
> > [ 14.719594] index -1 is out of range for type 'acpi_operand_object *[9]'
> > [ 14.719621] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0-rc3chromeavsrel1.0.184+ #1
> > [ 14.719657] Hardware name: Intel Corp. Geminilake/GLK RVP2 LP4SD (07), BIOS GELKRVPA.X64.0214.B50.2009111159 09/11/2020
> > [ 14.719694] Call Trace:
> > [ 14.719712] dump_stack_lvl+0x38/0x49
> > [ 14.719749] dump_stack+0x10/0x12
> > [ 14.719775] ubsan_epilogue+0x9/0x45
> > [ 14.719801] __ubsan_handle_out_of_bounds.cold+0x44/0x49
> > [ 14.719835] acpi_ds_exec_end_op+0x1d7/0x6b5
> > [ 14.719870] acpi_ps_parse_loop+0x942/0xb34
> > ...
> >
> > Problem happens because WalkState->NumOperands is 0 and it is used when
> > trying to access into operands table. Actual code is:
> > WalkState->Operands [WalkState->NumOperands -1]
> > which causes out of bound access. Improve the check before above access
> > to check if ACPI opcode should have any arguments (operands) at all.
> >
> > Link: https://github.com/acpica/acpica/pull/745
> > Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@xxxxxxxxxxxxxxx>
> > Reviewed-by: Cezary Rojewski <cezary.rojewski@xxxxxxxxx>
> > ---
> >   drivers/acpi/acpica/dswexec.c | 6 ++++--
> >   1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/acpi/acpica/dswexec.c b/drivers/acpi/acpica/dswexec.c
> > index e8ad41387f84..489c9b9d8d15 100644
> > --- a/drivers/acpi/acpica/dswexec.c
> > +++ b/drivers/acpi/acpica/dswexec.c
> > @@ -389,9 +389,11 @@ acpi_status acpi_ds_exec_end_op(struct acpi_walk_state *walk_state)
> >
> >                  /*
> >                   * All opcodes require operand resolution, with the only exceptions
> > -                * being the object_type and size_of operators.
> > +                * being the object_type and size_of operators as well as operands that
>
> Should this be "opcodes that take no arguments" rather?

Yes, it makes more sense that way. I've send v2 and updated pull request 
to acpica.

> > +                * take no arguments.
> >                   */
> > -               if (!(walk_state->op_info->flags & AML_NO_OPERAND_RESOLVE)) {
> > +               if (!(walk_state->op_info->flags & AML_NO_OPERAND_RESOLVE) &&
> > +                   (walk_state->op_info->flags & AML_HAS_ARGS)) {
> >
> >                          /* Resolve all operands */
> >
> > --