From:   Thomas Zimmermann <tzimmermann@suse.de>
To:     deller@gmx.de, paulus@samba.org, benh@kernel.crashing.org,
        linux@armlinux.org.uk, pjones@redhat.com, timur@kernel.org,
        adaplas@gmail.com, s.hauer@pengutronix.de, shawnguo@kernel.org,
        mbroemme@libmpq.org, thomas@winischhofer.net,
        James.Bottomley@HansenPartnership.com, spock@gentoo.org,
        sudipm.mukherjee@gmail.com, teddy.wang@siliconmotion.com,
        geert+renesas@glider.be, corbet@lwn.net
Cc:     linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org,
        Thomas Zimmermann <tzimmermann@suse.de>
Subject: [PATCH 15/99] fbdev/cirrusfb: Duplicate video-mode option string
Date:   Mon,  6 Mar 2023 16:58:52 +0100
Message-Id: <20230306160016.4459-16-tzimmermann@suse.de>
In-Reply-To: <20230306160016.4459-1-tzimmermann@suse.de>
References: <20230306160016.4459-1-tzimmermann@suse.de>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Assume that the driver does not own the option string or its substrings
and hence duplicate the option string for the video mode. The driver only
parses the option string once as part of module initialization, so use
a static buffer to store the duplicated mode option. Linux automatically
frees the memory upon releasing the module.

Done in preparation of switching the driver to struct option_iter and
constifying the option string.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/video/fbdev/cirrusfb.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/video/fbdev/cirrusfb.c b/drivers/video/fbdev/cirrusfb.c
index ba45e2147c52..fbf9281a7004 100644
--- a/drivers/video/fbdev/cirrusfb.c
+++ b/drivers/video/fbdev/cirrusfb.c
@@ -2336,10 +2336,20 @@ static int __init cirrusfb_setup(char *options)
 
 		if (!strcmp(this_opt, "noaccel"))
 			noaccel = 1;
-		else if (!strncmp(this_opt, "mode:", 5))
-			mode_option = this_opt + 5;
-		else
-			mode_option = this_opt;
+		else {
+			static char mode_option_buf[256];
+			int ret;
+
+			if (!strncmp(this_opt, "mode:", 5))
+				this_opt += 5;
+
+			ret = snprintf(mode_option_buf, sizeof(mode_option_buf), "%s", this_opt);
+			if (WARN(ret < 0, "cirrusfb: ignoring invalid option, ret=%d\n", ret))
+				continue;
+			if (WARN(ret >= sizeof(mode_option_buf), "cirrusfb: option too long\n"))
+				continue;
+			mode_option = mode_option_buf;
+		}
 	}
 	return 0;
 }
-- 
2.39.2