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staging: p9auth: prevent some oopses and memory leaks

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Before all testcases, do:
	mknod /dev/caphash c 253 0
	mknod /dev/capuse c 253 1

This patch does the following:

1. caphash write of > CAP_NODE_SIZE bytes overruns node_ptr->data
	(test: cat /etc/mime.types > /dev/caphash)
2. make sure we don't dereference a NULL cap_devices[0].head
	(test: cat serge@root@abab > /dev/capuse)
3. don't let strlen dereference a NULL target_user etc
	(test: echo ab > /dev/capuse)
4. Don't leak a bunch of memory in cap_write().  Note that
   technically node_ptr is not needed for the capuse write case.
   As a result I have a much more extensive patch splitting up
   cap_write(), but I thought a smaller patch that is easier to test
   and verify would be a better start.  To test:
	cnt=0
	while [ 1 ]; do
		echo /etc/mime.types > /dev/capuse
		if [ $((cnt%25)) -eq 0 ]; then
			head -2 /proc/meminfo
		fi
		cnt=$((cnt+1))
		sleep 0.3
	done
   Without this patch, it MemFree steadily drops.  With the patch,
   it does not.

I have *not* tested this driver (with or without these patches)
with factotum or anything - only using the tests described above.

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Serge E. Hallyn 2009-05-20 10:15:28 -05:00 committed by Greg Kroah-Hartman
parent 0f51010e87
commit f82ebea5c8
1 changed files with 23 additions and 1 deletions
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24
drivers/staging/p9auth/p9auth.c
View file

@ -180,8 +180,12 @@ static ssize_t cap_write(struct file *filp, const char __user *buf,
if (down_interruptible(&dev->sem))
return -ERESTARTSYS;
user_buf_running = NULL;
hash_str = NULL;
node_ptr = kmalloc(sizeof(struct cap_node), GFP_KERNEL);
user_buf = kzalloc(count, GFP_KERNEL);
if (!node_ptr || !user_buf)
goto out;
if (copy_from_user(user_buf, buf, count)) {
retval = -EFAULT;
@ -193,11 +197,21 @@ static ssize_t cap_write(struct file *filp, const char __user *buf,
* hashed capability supplied by the user to the list of hashes
*/
if (0 == iminor(filp->f_dentry->d_inode)) {
if (count > CAP_NODE_SIZE) {
retval = -EINVAL;
goto out;
}
printk(KERN_INFO "Capability being written to /dev/caphash : \n");
hexdump(user_buf, count);
memcpy(node_ptr->data, user_buf, count);
list_add(&(node_ptr->list), &(dev->head->list));
node_ptr = NULL;
} else {
if (!cap_devices[0].head ||
list_empty(&(cap_devices[0].head->list))) {
retval = -EINVAL;
goto out;
}
/*
* break the supplied string into tokens with @ as the
* delimiter If the string is "user1@user2@randomstring" we
@ -208,6 +222,10 @@ static ssize_t cap_write(struct file *filp, const char __user *buf,
source_user = strsep(&user_buf_running, "@");
target_user = strsep(&user_buf_running, "@");
rand_str = strsep(&user_buf_running, "@");
if (!source_user || !target_user || !rand_str) {
retval = -EINVAL;
goto out;
}
/* hash the string user1@user2 with rand_str as the key */
len = strlen(source_user) + strlen(target_user) + 1;
@ -224,7 +242,7 @@ static ssize_t cap_write(struct file *filp, const char __user *buf,
retval = -EFAULT;
goto out;
}
memcpy(node_ptr->data, result, CAP_NODE_SIZE);
memcpy(node_ptr->data, result, CAP_NODE_SIZE); /* why? */
/* Change the process's uid if the hash is present in the
* list of hashes
*/
@ -299,6 +317,10 @@ static ssize_t cap_write(struct file *filp, const char __user *buf,
dev->size = *f_pos;
out:
kfree(node_ptr);
kfree(user_buf);
kfree(user_buf_running);
kfree(hash_str);
up(&dev->sem);
return retval;
}