From: Kyle McMartin <kyle@mcmartin.ca>
Date: Tue, 7 Feb 2006 20:58:47 +0000 (-0800)
Subject: [PATCH] sys_hpux: fix strlen_user() race
X-Git-Tag: v2.6.16-rc3~117
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=1fcbf053e55e961112f237dc690129f0858156f1;p=linux-2.6-omap-h63xx.git

[PATCH] sys_hpux: fix strlen_user() race

Userspace can alter the string after the kernel has run strlen_user().

Also: the strlen_user() return value includes the \0, so fix that.

Also: handle EFAULT from strlen_user().

It's unlikely anyone is using this code.  Very, very unlikely.  If I
remember correctly, CONFIG_HPUX turns this code on, but one would actually
need CONFIG_BINFMT_SOM to load a binary that could cause a problem, and
BINFMT_SOM has had an #error in it for quite some time.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/arch/parisc/hpux/sys_hpux.c b/arch/parisc/hpux/sys_hpux.c
index 29b4d61898f..05273ccced0 100644
--- a/arch/parisc/hpux/sys_hpux.c
+++ b/arch/parisc/hpux/sys_hpux.c
@@ -468,19 +468,23 @@ int hpux_sysfs(int opcode, unsigned long arg1, unsigned long arg2)
 	if ( opcode == 1 ) { /* GETFSIND */	
 		len = strlen_user((char *)arg1);
 		printk(KERN_DEBUG "len of arg1 = %d\n", len);
-
-		fsname = (char *) kmalloc(len+1, GFP_KERNEL);
+		if (len == 0)
+			return 0;
+		fsname = (char *) kmalloc(len, GFP_KERNEL);
 		if ( !fsname ) {
 			printk(KERN_DEBUG "failed to kmalloc fsname\n");
 			return 0;
 		}
 
-		if ( copy_from_user(fsname, (char *)arg1, len+1) ) {
+		if ( copy_from_user(fsname, (char *)arg1, len) ) {
 			printk(KERN_DEBUG "failed to copy_from_user fsname\n");
 			kfree(fsname);
 			return 0;
 		}
 
+		/* String could be altered by userspace after strlen_user() */
+		fsname[len] = '\0';
+
 		printk(KERN_DEBUG "that is '%s' as (char *)\n", fsname);
 		if ( !strcmp(fsname, "hfs") ) {
 			fstype = 0;