linux-kernel - [PATCH 1/5] drm/modes: parse_cmdline: Handle empty mode name part

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Date:   Fri,  8 Jul 2022 20:21:25 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Hans de Goede <hdegoede@...hat.com>
Cc:     dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
        linux-m68k@...r.kernel.org, linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH 1/5] drm/modes: parse_cmdline: Handle empty mode name part

If no mode name part was specified, mode_end is zero, and the "ret ==
mode_end" check does the wrong thing.

Fix this by checking for a non-zero return value instead.
While at it, skip all named mode handling when mode_end is zero, as it
is futile.

Fixes: 7b1cce760afe38b4 ("drm/modes: parse_cmdline: Allow specifying stand-alone options")
Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
---
 drivers/gpu/drm/drm_modes.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 14b746f7ba975954..30a7be97707bfb16 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -1823,9 +1823,9 @@ bool drm_mode_parse_command_line_for_connector(const char *mode_option,
 	}
 
 	/* First check for a named mode */
-	for (i = 0; i < ARRAY_SIZE(drm_named_modes_whitelist); i++) {
+	for (i = 0; mode_end && i < ARRAY_SIZE(drm_named_modes_whitelist); i++) {
 		ret = str_has_prefix(name, drm_named_modes_whitelist[i]);
-		if (ret == mode_end) {
+		if (ret) {
 			if (refresh_ptr)
 				return false; /* named + refresh is invalid */
 
-- 
2.25.1