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/tdfxfb.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/tdfxfb.c b/drivers/video/fbdev/tdfxfb.c
index d17e5e1472aa..ed3d8491e724 100644
--- a/drivers/video/fbdev/tdfxfb.c
+++ b/drivers/video/fbdev/tdfxfb.c
@@ -1589,7 +1589,15 @@ static void __init tdfxfb_setup(char *options)
 		} else if (!strncmp(this_opt, "nomtrr", 6)) {
 			nomtrr = 1;
 		} else {
-			mode_option = this_opt;
+			static char mode_option_buf[256];
+			int ret;
+
+			ret = snprintf(mode_option_buf, sizeof(mode_option_buf), "%s", this_opt);
+			if (WARN(ret < 0, "tdfxfb: ignoring invalid option, ret=%d\n", ret))
+				continue;
+			if (WARN(ret >= sizeof(mode_option_buf), "tdfxfb: option too long\n"))
+				continue;
+			mode_option = mode_option_buf;
 		}
 	}
 }
-- 
2.39.2