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 75/99] fbdev/sm712fb: Duplicate video-mode option string
Date:   Mon,  6 Mar 2023 16:59:52 +0100
Message-Id: <20230306160016.4459-76-tzimmermann@suse.de>
In-Reply-To: <20230306160016.4459-1-tzimmermann@suse.de>
References: <20230306160016.4459-1-tzimmermann@suse.de>
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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 constifying the option string.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/video/fbdev/sm712fb.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/sm712fb.c b/drivers/video/fbdev/sm712fb.c
index b528776c7612..b0f3898125f4 100644
--- a/drivers/video/fbdev/sm712fb.c
+++ b/drivers/video/fbdev/sm712fb.c
@@ -1761,8 +1761,21 @@ static int __init sm712fb_init(void)
 
 	if (fb_get_options("sm712fb", &option))
 		return -ENODEV;
-	if (option && *option)
-		mode_option = option;
+
+	if (option && *option) {
+		do {
+			static char mode_option_buf[256];
+			int ret;
+
+			ret = snprintf(mode_option_buf, sizeof(mode_option_buf), "%s", option);
+			if (WARN(ret < 0, "sm712fb: ignoring invalid option, ret=%d\n", ret))
+				continue;
+			if (WARN(ret >= sizeof(mode_option_buf), "sm712fb: option too long\n"))
+				continue;
+			mode_option = mode_option_buf;
+		} while (0);
+	}
+
 	sm7xx_vga_setup(mode_option);
 
 	return pci_register_driver(&smtcfb_driver);
-- 
2.39.2