From f82ebea5c8ef9ed9378fc6402051a4860a805397 Mon Sep 17 00:00:00 2001 From: "Serge E. Hallyn" Date: Wed, 20 May 2009 10:15:28 -0500 Subject: [PATCH] staging: p9auth: prevent some oopses and memory leaks 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 Signed-off-by: Greg Kroah-Hartman --- drivers/staging/p9auth/p9auth.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) 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@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; } -- 2.7.4