[PATCH 5.15 11/69] drm/simpledrm: Fix return type of simpledrm_simple_display_pipe_mode_valid()

Greg Kroah-Hartman
2022-08-01T12:04:33Z

From: Nathan Chancellor <nathan@kernel.org>

commit 0c09bc33aa8e9dc867300acaadc318c2f0d85a1e upstream.

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@vger.kernel.org
Fixes: 11e8f5fd223b ("drm: Add simpledrm driver")
Link: https://github.com/ClangBuiltLinux/linux/issues/1647
Reported-by: Tomasz Paweł Gajc <tpgxyz@gmail.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220725233629.223223-1-nathan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/tiny/simpledrm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c
@@ -614,7 +614,7 @@ static const struct drm_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)
{