[PATCH RFC 1/5] mfd: ls2kbmc: make a copy when parsing mode string

[Miao Wang via B4 Relay <devnull+shankerwangmiao.gmail.com@kernel.org>]

From: Miao Wang <shankerwangmiao@gmail.com>

When parsing the mode string from BMC, the string is manipulated
in-place with strsep(), preventing from parsing it again. Make a copy of
the original string and manipulate the copy instead to fix this.

Fixes: 0d64f6d1ffe9 ("mfd: ls2kbmc: Introduce Loongson-2K BMC core driver")
Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
 drivers/mfd/ls2k-bmc-core.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/mfd/ls2k-bmc-core.c b/drivers/mfd/ls2k-bmc-core.c
index 408056bfb2fe757a5bde43775a483a48352e706d..30b275bc48794a22249aeb8ba805ef78772d3466 100644
--- a/drivers/mfd/ls2k-bmc-core.c
+++ b/drivers/mfd/ls2k-bmc-core.c
@@ -427,34 +427,53 @@ static int ls2k_bmc_init(struct ls2k_bmc_ddata *ddata)
  */
 static int ls2k_bmc_parse_mode(struct pci_dev *pdev, struct simplefb_platform_data *pd)
 {
-	char *mode;
+	/* Assume 1024 bytes is enough for the resolution string */
+	char mode_buf[1024];
+	char *mode = mode_buf;
+	const void __iomem *mode_base;
 	int depth, ret;
 
 	/* The last 16M of PCI BAR0 is used to store the resolution string. */
-	mode = devm_ioremap(&pdev->dev, pci_resource_start(pdev, 0) + SZ_16M, SZ_16M);
-	if (!mode)
+	mode_base = devm_ioremap(&pdev->dev, pci_resource_start(pdev, 0) + SZ_16M,
+				 sizeof(mode_buf));
+	if (!mode_base)
 		return -ENOMEM;
+	memcpy(mode_buf, mode_base, sizeof(mode_buf) - 1);
+	mode_buf[sizeof(mode_buf) - 1] = '\0';
+	devm_iounmap(&pdev->dev, (void __iomem *)mode_base);
 
 	/* The resolution field starts with the flag "video=". */
 	if (!strncmp(mode, "video=", 6))
 		mode = mode + 6;
+	else
+		goto invalid_mode;
 
 	ret = kstrtoint(strsep(&mode, "x"), 10, &pd->width);
 	if (ret)
 		return ret;
+	if (mode == NULL)
+		goto invalid_mode;
 
 	ret = kstrtoint(strsep(&mode, "-"), 10, &pd->height);
 	if (ret)
 		return ret;
+	if (mode == NULL)
+		goto invalid_mode;
 
 	ret = kstrtoint(strsep(&mode, "@"), 10, &depth);
 	if (ret)
 		return ret;
+	if (mode == NULL)
+		goto invalid_mode;
 
 	pd->stride = pd->width * depth / 8;
 	pd->format = depth == 32 ? "a8r8g8b8" : "r5g6b5";
 
 	return 0;
+
+invalid_mode:
+	dev_err(&pdev->dev, "Invalid resolution string: %s\n", mode_buf);
+	return -EINVAL;
 }
 
 static int ls2k_bmc_probe(struct pci_dev *dev, const struct pci_device_id *id)

-- 
2.49.0