Re: [PATCH] drm/simpledrm: Fix return type of simpledrm_simple_display_pipe_mode_valid()

[Thomas Zimmermann]

Hi

Am 26.07.22 um 02:12 schrieb Sami Tolvanen:
> On Mon, Jul 25, 2022 at 4:37 PM Nathan Chancellor <nathan@xxxxxxxxxx> wrote:
> > When booting a kernel compiled with clang's CFI protection
> > (CONFIG_CFI_CLANG), there is a CFI failure in
> > drm_simple_kms_crtc_mode_valid() when trying to call
> > simpledrm_simple_display_pipe_mode_valid() through ->mode_valid():
> >
> > [    0.322802] CFI failure (target: simpledrm_simple_display_pipe_mode_valid+0x0/0x8):
> > ...
> > [    0.324928] Call trace:
> > [    0.324969]  __ubsan_handle_cfi_check_fail+0x58/0x60
> > [    0.325053]  __cfi_check_fail+0x3c/0x44
> > [    0.325120]  __cfi_slowpath_diag+0x178/0x200
> > [    0.325192]  drm_simple_kms_crtc_mode_valid+0x58/0x80
> > [    0.325279]  __drm_helper_update_and_validate+0x31c/0x464
> > ...
> >
> > The ->mode_valid() member in 'struct drm_simple_display_pipe_funcs'
> > expects a return type of 'enum drm_mode_status', not 'int'. Correct it
> > to fix the CFI failure.
> >
> > Cc: stable@xxxxxxxxxxxxxxx
> > Fixes: 11e8f5fd223b ("drm: Add simpledrm driver")
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1647
> > Reported-by: Tomasz Paweł Gajc <tpgxyz@xxxxxxxxx>
> > Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/tiny/simpledrm.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
> > index 768242a78e2b..5422363690e7 100644
> > --- a/drivers/gpu/drm/tiny/simpledrm.c
> > +++ b/drivers/gpu/drm/tiny/simpledrm.c
> > @@ -627,7 +627,7 @@ static const struct drm_connector_funcs simpledrm_connector_funcs = {
> >          .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> >   };
> >
> > -static int
> > +static enum drm_mode_status
> >   simpledrm_simple_display_pipe_mode_valid(struct drm_simple_display_pipe *pipe,
> >                                      const struct drm_display_mode *mode)
> >   {
>
> Thanks for fixing this, Nathan! The patch looks correct to me.
>
> Reviewed-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>

Thanks a lot. I've added the patch to drm-misc-fixes.

Best regards
Thomas

> Sami

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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