linux-kernel - [PATCH RFC] brcmfmac: sanitize DMI strings

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Date:   Sun, 5 May 2019 16:48:52 +0200
From:   Victor Bravo <1905@...blk.com>
To:     Arend Van Spriel <arend.vanspriel@...adcom.com>
Cc:     Franky Lin <franky.lin@...adcom.com>,
        Hante Meuleman <hante.meuleman@...adcom.com>,
        Chi-Hsien Lin <chi-hsien.lin@...ress.com>,
        Wright Feng <wright.feng@...ress.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        linux-wireless@...r.kernel.org,
        brcm80211-dev-list.pdl@...adcom.com,
        brcm80211-dev-list@...ress.com, linux-kernel@...r.kernel.org,
        Hans de Goede <hdegoede@...hat.com>
Subject: [PATCH RFC] brcmfmac: sanitize DMI strings

Sanitize DMI strings in brcmfmac driver to make resulting filenames
contain only safe characters. This version replaces all non-printable
characters incl. delete (0-31, 127-255), spaces and slashes with
underscores.

This change breaks backward compatibility, but adds control over strings
passed to firmware loader and compatibility with CONFIG_EXTRA_FIRMWARE
which doesn't support spaces in filenames.

Signed-off-by: Victor Bravo <1905@...blk.com>

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/dmi.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/dmi.c
index 7535cb0d4ac0..fa654ce7172b 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/dmi.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/dmi.c
@@ -23,6 +23,14 @@
 /* The DMI data never changes so we can use a static buf for this */
 static char dmi_board_type[128];
 
+/* Array of 128 bits representing 7-bit characters allowed in DMI strings. */
+static unsigned char brcmf_dmi_allowed_chars[] = {
+	0x00, 0x00, 0x00, 0x00, 0xfe, 0x7f, 0xff, 0xff,
+	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f
+};
+
+#define BRCMF_DMI_SAFE_CHAR '_'
+
 struct brcmf_dmi_data {
 	u32 chip;
 	u32 chiprev;
@@ -43,10 +51,6 @@ static const struct brcmf_dmi_data meegopad_t08_data = {
 	BRCM_CC_43340_CHIP_ID, 2, "meegopad-t08"
 };
 
-static const struct brcmf_dmi_data pov_tab_p1006w_data = {
-	BRCM_CC_43340_CHIP_ID, 2, "pov-tab-p1006w-data"
-};
-
 static const struct dmi_system_id dmi_platform_data[] = {
 	{
 		/* Match for the GPDwin which unfortunately uses somewhat
@@ -85,20 +89,18 @@ static const struct dmi_system_id dmi_platform_data[] = {
 		},
 		.driver_data = (void *)&meegopad_t08_data,
 	},
-	{
-		/* Point of View TAB-P1006W-232 */
-		.matches = {
-			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "Insyde"),
-			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "BayTrail"),
-			/* Note 105b is Foxcon's USB/PCI vendor id */
-			DMI_EXACT_MATCH(DMI_BOARD_VENDOR, "105B"),
-			DMI_EXACT_MATCH(DMI_BOARD_NAME, "0E57"),
-		},
-		.driver_data = (void *)&pov_tab_p1006w_data,
-	},
 	{}
 };
 
+void brcmf_dmi_sanitize(char *dst, const unsigned char *allowed, char safe)
+{
+	while (*dst) {
+		if ((*dst < 0) || !(allowed[*dst / 8] & (1 << (*dst % 8))))
+			*dst = safe;
+		dst++;
+	}
+}
+
 void brcmf_dmi_probe(struct brcmf_mp_device *settings, u32 chip, u32 chiprev)
 {
 	const struct dmi_system_id *match;
@@ -126,6 +128,9 @@ void brcmf_dmi_probe(struct brcmf_mp_device *settings, u32 chip, u32 chiprev)
 	if (sys_vendor && product_name) {
 		snprintf(dmi_board_type, sizeof(dmi_board_type), "%s-%s",
 			 sys_vendor, product_name);
+		brcmf_dmi_sanitize(dmi_board_type,
+				   brcmf_dmi_allowed_chars,
+				   BRCMF_DMI_SAFE_CHAR);
 		settings->board_type = dmi_board_type;
 	}
 }