From: Serge E. Hallyn <serue at us.ibm.com>
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 at 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 at us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at suse.de>
---
drivers/staging/p9auth/p9auth.c | 24 +++++++++++++++++++++++-
1 files changed, 23 insertions(+), 1 deletions(-)
diff --git a/drivers/staging/p9auth/p9auth.c b/drivers/staging/p9auth/p9auth.c
index 3cac89b..9111dcb 100644
--- a/drivers/staging/p9auth/p9auth.c
+++ b/drivers/staging/p9auth/p9auth.c
@@ -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 at 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 at 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;
}
--
1.6.3.2
