Hi, Nathan: Nathan Chancellor <nathan@xxxxxxxxxx> 於 2022年11月2日 週三 晚上11:47寫道： > > With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG), > indirect call targets are validated against the expected function > pointer prototype to make sure the call target is valid to help mitigate > ROP attacks. If they are not identical, there is a failure at run time, > which manifests as either a kernel panic or thread getting killed. A > proposed warning in clang aims to catch these at compile time, which > reveals: > > drivers/gpu/drm/mediatek/mtk_hdmi.c:1407:16: error: incompatible function pointer types initializing 'enum drm_mode_status (*)(struct drm_bridge *, const struct drm_display_info *, const struct drm_display_mode *)' with an expression of type 'int (struct drm_bridge *, const struct drm_display_info *, const struct drm_display_mode *)' [-Werror,-Wincompatible-function-pointer-types-strict] > .mode_valid = mtk_hdmi_bridge_mode_valid, > ^~~~~~~~~~~~~~~~~~~~~~~~~~ > 1 error generated. > > ->mode_valid() in 'struct drm_bridge_funcs' expects a return type of > 'enum drm_mode_status', not 'int'. Adjust the return type of > mtk_hdmi_bridge_mode_valid() to match the prototype's to resolve the > warning and CFI failure. Applied to mediatek-drm-next [1], thanks. [1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-next Chun-Kuang. > > Link: https://github.com/ClangBuiltLinux/linux/issues/1750 > Reported-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx> > Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx> > --- > drivers/gpu/drm/mediatek/mtk_hdmi.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c > index 4c80b6896dc3..6e8f99554f54 100644 > --- a/drivers/gpu/drm/mediatek/mtk_hdmi.c > +++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c > @@ -1202,9 +1202,10 @@ static enum drm_connector_status mtk_hdmi_detect(struct mtk_hdmi *hdmi) > return mtk_hdmi_update_plugged_status(hdmi); > } > > -static int mtk_hdmi_bridge_mode_valid(struct drm_bridge *bridge, > - const struct drm_display_info *info, > - const struct drm_display_mode *mode) > +static enum drm_mode_status > +mtk_hdmi_bridge_mode_valid(struct drm_bridge *bridge, > + const struct drm_display_info *info, > + const struct drm_display_mode *mode) > { > struct mtk_hdmi *hdmi = hdmi_ctx_from_bridge(bridge); > struct drm_bridge *next_bridge; > > base-commit: 9abf2313adc1ca1b6180c508c25f22f9395cc780 > -- > 2.38.1 >
