linux-kernel - Re: [ 88.628451] BUG: unable to handle kernel paging request at f8dbf000 "isight

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 6 Jun 2008 13:11:36 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Justin Mattock <justinmattock@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-usb@...r.kernel.org
Subject: Re: [ 88.628451] BUG: unable to handle kernel paging request at f8dbf000 "isight_firmware"

Argh. My firmware image contained the 0x8001 token that indicates end of 
firmware - the ones generated by Etienne's tool don't, so the driver 
reads straight off the end of the buffer. Can you try this patch? It 
also incorporates the cleanups Andrew suggested, and should be resistant 
to malformed data.

diff --git a/drivers/usb/misc/isight_firmware.c b/drivers/usb/misc/isight_firmware.c
index 390e048..cc5943c 100644
--- a/drivers/usb/misc/isight_firmware.c
+++ b/drivers/usb/misc/isight_firmware.c
@@ -39,9 +39,9 @@ static int isight_firmware_load(struct usb_interface *intf,
 	struct usb_device *dev = interface_to_usbdev(intf);
 	int llen, len, req, ret = 0;
 	const struct firmware *firmware;
-	unsigned char *buf;
+	unsigned char *buf = kmalloc(50, GFP_KERNEL);
 	unsigned char data[4];
-	char *ptr;
+	u8 *ptr;
 
 	if (request_firmware(&firmware, "isight.fw", &dev->dev) != 0) {
 		printk(KERN_ERR "Unable to load isight firmware\n");
@@ -59,7 +59,7 @@ static int isight_firmware_load(struct usb_interface *intf,
 		goto out;
 	}
 
-	while (1) {
+	while (ptr+4 <= firmware->data+firmware->size) {
 		memcpy(data, ptr, 4);
 		len = (data[0] << 8 | data[1]);
 		req = (data[2] << 8 | data[3]);
@@ -71,10 +71,14 @@ static int isight_firmware_load(struct usb_interface *intf,
 			continue;
 
 		for (; len > 0; req += 50) {
-			llen = len > 50 ? 50 : len;
+			llen = min (len, 50);		  
 			len -= llen;
-
-			buf = kmalloc(llen, GFP_KERNEL);
+			if (ptr+llen > firmware->data+firmware->size) {
+				printk (KERN_ERR 
+					"Malformed isight firmware");
+				ret = -ENODEV;
+				goto out;
+			}
 			memcpy(buf, ptr, llen);
 
 			ptr += llen;
@@ -89,16 +93,18 @@ static int isight_firmware_load(struct usb_interface *intf,
 				goto out;
 			}
 
-			kfree(buf);
 		}
 	}
+
 	if (usb_control_msg
 	    (dev, usb_sndctrlpipe(dev, 0), 0xa0, 0x40, 0xe600, 0, "\0", 1,
 	     300) != 1) {
 		printk(KERN_ERR "isight firmware loading completion failed\n");
 		ret = -ENODEV;
 	}
+
 out:
+	kfree(buf);
 	release_firmware(firmware);
 	return ret;
 }

-- 
Matthew Garrett | mjg59@...f.ucam.org
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/