From 1fcbf053e55e961112f237dc690129f0858156f1 Mon Sep 17 00:00:00 2001
From: Kyle McMartin <kyle@mcmartin.ca>
Date: Tue, 7 Feb 2006 12:58:47 -0800
Subject: [PATCH] [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>
---
arch/parisc/hpux/sys_hpux.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/parisc/hpux/sys_hpux.c b/arch/parisc/hpux/sys_hpux.c
index 29b4d61898f2c..05273ccced0e5 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;
--
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