From: Edward Adam Davis <eadavis@qq.com>
Date: Mon, 3 Nov 2025 11:57:49 +0000 (+0800)
Subject: media: dvb-usb: pctv452e: move snd/rcv len check before kmalloc
X-Git-Tag: v6.19-rc1~159^2~89
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1a31cb2782104969e48c7ce7e4fc06e403fcb5cf;p=thirdparty%2Fkernel%2Flinux.git

media: dvb-usb: pctv452e: move snd/rcv len check before kmalloc

syzbot reported a uninit-value in pctv452e_i2c_msg. [1]

When the snd_len or rcv_len check fails and jumps to failed, buf is
uninitialized, triggering the uninit-value issue.

Move the snd/rcv length check before kmalloc, and return -EINVAL directly
if the condition is met.

[1]
BUG: KMSAN: uninit-value in hex_string+0x681/0x740 lib/vsprintf.c:1220
 pctv452e_i2c_msg+0x82a/0x8f0 drivers/media/usb/dvb-usb/pctv452e.c:467
 pctv452e_i2c_xfer+0x2e6/0x4c0 drivers/media/usb/dvb-usb/pctv452e.c:502

Reported-by: syzbot+480edd2cadb85ddb4bbe@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=480edd2cadb85ddb4bbe
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
---

diff --git a/drivers/media/usb/dvb-usb/pctv452e.c b/drivers/media/usb/dvb-usb/pctv452e.c
index 5094de9a312e8..bc7a224d829e3 100644
--- a/drivers/media/usb/dvb-usb/pctv452e.c
+++ b/drivers/media/usb/dvb-usb/pctv452e.c
@@ -422,16 +422,15 @@ static int pctv452e_i2c_msg(struct dvb_usb_device *d, u8 addr,
 	u8 id;
 	int ret;
 
+	if (snd_len > 64 - 7 || rcv_len > 64 - 7)
+		return -EINVAL;
+
 	buf = kmalloc(64, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
 	id = state->c++;
 
-	ret = -EINVAL;
-	if (snd_len > 64 - 7 || rcv_len > 64 - 7)
-		goto failed;
-
 	buf[0] = SYNC_BYTE_OUT;
 	buf[1] = id;
 	buf[2] = PCTV_CMD_I2C;