media: gspca: zero usb_buf on error

BugLink: https://bugs.launchpad.net/bugs/1848589

[ Upstream commit 4843a543 ]

If reg_r() fails, then gspca_dev->usb_buf was left uninitialized,
and some drivers used the contents of that buffer in logic.

This caused several syzbot errors:

https://syzkaller.appspot.com/bug?extid=397fd082ce5143e2f67d
https://syzkaller.appspot.com/bug?extid=1a35278dd0ebfb3a038a
https://syzkaller.appspot.com/bug?extid=06ddf1788cfd048c5e82

I analyzed the gspca drivers and zeroed the buffer where needed.

Reported-and-tested-by: syzbot+1a35278dd0ebfb3a038a@syzkaller.appspotmail.com
Reported-and-tested-by: syzbot+397fd082ce5143e2f67d@syzkaller.appspotmail.com
Reported-and-tested-by: syzbot+06ddf1788cfd048c5e82@syzkaller.appspotmail.com
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/media/usb/gspca/konica.c

@@ -127,6 +127,11 @@ static void reg_r(struct gspca_dev *gspca_dev, u16 value, u16 index)
 	if (ret < 0) {
 		pr_err("reg_r err %d\n", ret);
 		gspca_dev->usb_err = ret;
+		/*
+		 * Make sure the buffer is zeroed to avoid uninitialized
+		 * values.
+		 */
+		memset(gspca_dev->usb_buf, 0, 2);
 	}
 }
 

drivers/media/usb/gspca/nw80x.c

@@ -1584,6 +1584,11 @@ static void reg_r(struct gspca_dev *gspca_dev,
 	if (ret < 0) {
 		pr_err("reg_r err %d\n", ret);
 		gspca_dev->usb_err = ret;
+		/*
+		 * Make sure the buffer is zeroed to avoid uninitialized
+		 * values.
+		 */
+		memset(gspca_dev->usb_buf, 0, USB_BUF_SZ);
 		return;
 	}
 	if (len == 1)

drivers/media/usb/gspca/ov519.c

@@ -2116,6 +2116,11 @@ static int reg_r(struct sd *sd, u16 index)
 	} else {
 		PERR("reg_r %02x failed %d\n", index, ret);
 		sd->gspca_dev.usb_err = ret;
+		/*
+		 * Make sure the result is zeroed to avoid uninitialized
+		 * values.
+		 */
+		gspca_dev->usb_buf[0] = 0;
 	}
 
 	return ret;
@@ -2142,6 +2147,11 @@ static int reg_r8(struct sd *sd,
 	} else {
 		PERR("reg_r8 %02x failed %d\n", index, ret);
 		sd->gspca_dev.usb_err = ret;
+		/*
+		 * Make sure the buffer is zeroed to avoid uninitialized
+		 * values.
+		 */
+		memset(gspca_dev->usb_buf, 0, 8);
 	}
 
 	return ret;

drivers/media/usb/gspca/ov534.c

@@ -644,6 +644,11 @@ static u8 ov534_reg_read(struct gspca_dev *gspca_dev, u16 reg)
 	if (ret < 0) {
 		pr_err("read failed %d\n", ret);
 		gspca_dev->usb_err = ret;
+		/*
+		 * Make sure the result is zeroed to avoid uninitialized
+		 * values.
+		 */
+		gspca_dev->usb_buf[0] = 0;
 	}
 	return gspca_dev->usb_buf[0];
 }

drivers/media/usb/gspca/ov534_9.c

@@ -1157,6 +1157,7 @@ static u8 reg_r(struct gspca_dev *gspca_dev, u16 reg)
 	if (ret < 0) {
 		pr_err("reg_r err %d\n", ret);
 		gspca_dev->usb_err = ret;
+		return 0;
 	}
 	return gspca_dev->usb_buf[0];
 }

drivers/media/usb/gspca/se401.c

@@ -115,6 +115,11 @@ static void se401_read_req(struct gspca_dev *gspca_dev, u16 req, int silent)
 			pr_err("read req failed req %#04x error %d\n",
 			       req, err);
 		gspca_dev->usb_err = err;
+		/*
+		 * Make sure the buffer is zeroed to avoid uninitialized
+		 * values.
+		 */
+		memset(gspca_dev->usb_buf, 0, READ_REQ_SIZE);
 	}
 }
 

drivers/media/usb/gspca/sn9c20x.c

@@ -924,6 +924,11 @@ static void reg_r(struct gspca_dev *gspca_dev, u16 reg, u16 length)
 	if (unlikely(result < 0 || result != length)) {
 		pr_err("Read register %02x failed %d\n", reg, result);
 		gspca_dev->usb_err = result;
+		/*
+		 * Make sure the buffer is zeroed to avoid uninitialized
+		 * values.
+		 */
+		memset(gspca_dev->usb_buf, 0, USB_BUF_SZ);
 	}
 }
 

drivers/media/usb/gspca/sonixb.c

@@ -466,6 +466,11 @@ static void reg_r(struct gspca_dev *gspca_dev,
 		dev_err(gspca_dev->v4l2_dev.dev,
 			"Error reading register %02x: %d\n", value, res);
 		gspca_dev->usb_err = res;
+		/*
+		 * Make sure the result is zeroed to avoid uninitialized
+		 * values.
+		 */
+		gspca_dev->usb_buf[0] = 0;
 	}
 }
 

drivers/media/usb/gspca/sonixj.c

@@ -1175,6 +1175,11 @@ static void reg_r(struct gspca_dev *gspca_dev,
 	if (ret < 0) {
 		pr_err("reg_r err %d\n", ret);
 		gspca_dev->usb_err = ret;
+		/*
+		 * Make sure the buffer is zeroed to avoid uninitialized
+		 * values.
+		 */
+		memset(gspca_dev->usb_buf, 0, USB_BUF_SZ);
 	}
 }
 

drivers/media/usb/gspca/spca1528.c

@@ -84,6 +84,11 @@ static void reg_r(struct gspca_dev *gspca_dev,
 	if (ret < 0) {
 		pr_err("reg_r err %d\n", ret);
 		gspca_dev->usb_err = ret;
+		/*
+		 * Make sure the buffer is zeroed to avoid uninitialized
+		 * values.
+		 */
+		memset(gspca_dev->usb_buf, 0, USB_BUF_SZ);
 	}
 }
 

drivers/media/usb/gspca/sq930x.c

@@ -438,6 +438,11 @@ static void reg_r(struct gspca_dev *gspca_dev,
 	if (ret < 0) {
 		pr_err("reg_r %04x failed %d\n", value, ret);
 		gspca_dev->usb_err = ret;
+		/*
+		 * Make sure the buffer is zeroed to avoid uninitialized
+		 * values.
+		 */
+		memset(gspca_dev->usb_buf, 0, USB_BUF_SZ);
 	}
 }
 

drivers/media/usb/gspca/sunplus.c

@@ -268,6 +268,11 @@ static void reg_r(struct gspca_dev *gspca_dev,
 	if (ret < 0) {
 		pr_err("reg_r err %d\n", ret);
 		gspca_dev->usb_err = ret;
+		/*
+		 * Make sure the buffer is zeroed to avoid uninitialized
+		 * values.
+		 */
+		memset(gspca_dev->usb_buf, 0, USB_BUF_SZ);
 	}
 }
 

drivers/media/usb/gspca/vc032x.c

@@ -2919,6 +2919,11 @@ static void reg_r_i(struct gspca_dev *gspca_dev,
 	if (ret < 0) {
 		pr_err("reg_r err %d\n", ret);
 		gspca_dev->usb_err = ret;
+		/*
+		 * Make sure the buffer is zeroed to avoid uninitialized
+		 * values.
+		 */
+		memset(gspca_dev->usb_buf, 0, USB_BUF_SZ);
 	}
 }
 static void reg_r(struct gspca_dev *gspca_dev,

drivers/media/usb/gspca/w996Xcf.c

@@ -139,6 +139,11 @@ static int w9968cf_read_sb(struct sd *sd)
 	} else {
 		pr_err("Read SB reg [01] failed\n");
 		sd->gspca_dev.usb_err = ret;
+		/*
+		 * Make sure the buffer is zeroed to avoid uninitialized
+		 * values.
+		 */
+		memset(sd->gspca_dev.usb_buf, 0, 2);
 	}
 
 	udelay(W9968CF_I2C_BUS_DELAY);