linux-kernel - Re: [Patch 0/2] powerpc: avoid userspace poking to legacy ioports

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Message-ID: <20080213183506.7f3e3145@de.ibm.com>
Date:	Wed, 13 Feb 2008 18:35:06 +0100
From:	Christian Krafft <krafft@...ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	parabelboi@...serverein.de, linuxppc-dev@...abs.org
Subject: Re: [Patch 0/2] powerpc: avoid userspace poking to legacy ioports

sensors_detect crashes kernel on PowerPC, as it pokes directly to memory.
This patch adds a check_legacy_ioports to read_port and write_port.
It will now return ENXIO, instead of oopsing.

Signed-off-by: Christian Krafft <krafft@...ibm.com>

Index: linux.git/drivers/char/mem.c
===================================================================
--- linux.git.orig/drivers/char/mem.c
+++ linux.git/drivers/char/mem.c
@@ -566,8 +566,13 @@ static ssize_t read_port(struct file * f
 	char __user *tmp = buf;
 
 	if (!access_ok(VERIFY_WRITE, buf, count))
-		return -EFAULT; 
+		return -EFAULT;
+
 	while (count-- > 0 && i < 65536) {
+#ifdef CONFIG_PPC_MERGE
+		if (check_legacy_ioport(i))
+			return -ENXIO;
+#endif
 		if (__put_user(inb(i),tmp) < 0) 
 			return -EFAULT;  
 		i++;
@@ -585,6 +590,7 @@ static ssize_t write_port(struct file * 
 
 	if (!access_ok(VERIFY_READ,buf,count))
 		return -EFAULT;
+
 	while (count-- > 0 && i < 65536) {
 		char c;
 		if (__get_user(c, tmp)) {
@@ -592,6 +598,10 @@ static ssize_t write_port(struct file * 
 				break;
 			return -EFAULT; 
 		}
+#ifdef CONFIG_PPC_MERGE
+		if (check_legacy_ioport(i))
+			return -ENXIO;
+#endif
 		outb(c,i);
 		i++;
 		tmp++;


-- 
Mit freundlichen Gruessen,
kind regards,

Christian Krafft
IBM Systems & Technology Group,
Linux Kernel Development
IT Specialist


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