linux-kernel - [PATCH 31/99] fbdev/hyperv_fb: Duplicate video-mode option string

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Date:   Mon,  6 Mar 2023 16:59:08 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     deller@....de, paulus@...ba.org, benh@...nel.crashing.org,
        linux@...linux.org.uk, pjones@...hat.com, timur@...nel.org,
        adaplas@...il.com, s.hauer@...gutronix.de, shawnguo@...nel.org,
        mbroemme@...mpq.org, thomas@...ischhofer.net,
        James.Bottomley@...senPartnership.com, spock@...too.org,
        sudipm.mukherjee@...il.com, teddy.wang@...iconmotion.com,
        geert+renesas@...der.be, corbet@....net
Cc:     linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org,
        Thomas Zimmermann <tzimmermann@...e.de>
Subject: [PATCH 31/99] fbdev/hyperv_fb: Duplicate video-mode option string

Assume that the driver does not own the option string or its substrings
and hence duplicate the option string for the video mode. As the driver
implements a very simple mode parser in a fairly unstructured way, just
duplicate the option string and parse the duplicated memory buffer. Free
the buffer afterwards.

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

Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
---
 drivers/video/fbdev/hyperv_fb.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
index 4a6a3303b6b4..edb0555239c6 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -903,17 +903,23 @@ static const struct fb_ops hvfb_ops = {
 static void hvfb_get_option(struct fb_info *info)
 {
 	struct hvfb_par *par = info->par;
-	char *opt = NULL, *p;
+	char *options = NULL;
+	char *optbuf, *opt, *p;
 	uint x = 0, y = 0;
 
-	if (fb_get_options(KBUILD_MODNAME, &opt) || !opt || !*opt)
+	if (fb_get_options(KBUILD_MODNAME, &options) || !options || !*options)
 		return;
 
+	optbuf = kstrdup(options, GFP_KERNEL);
+	if (!optbuf)
+		return;
+	opt = optbuf;
+
 	p = strsep(&opt, "x");
 	if (!*p || kstrtouint(p, 0, &x) ||
 	    !opt || !*opt || kstrtouint(opt, 0, &y)) {
 		pr_err("Screen option is invalid: skipped\n");
-		return;
+		goto out;
 	}
 
 	if (x < HVFB_WIDTH_MIN || y < HVFB_HEIGHT_MIN ||
@@ -922,12 +928,14 @@ static void hvfb_get_option(struct fb_info *info)
 	    (par->synthvid_version == SYNTHVID_VERSION_WIN8 &&
 	     x * y * screen_depth / 8 > SYNTHVID_FB_SIZE_WIN8)) {
 		pr_err("Screen resolution option is out of range: skipped\n");
-		return;
+		goto out;
 	}
 
 	screen_width = x;
 	screen_height = y;
-	return;
+
+out:
+	kfree(optbuf);
 }
 
 /*
-- 
2.39.2