eCryptfs: NULL pointer dereference in ecryptfs_send_miscdev()

If data is NULL, msg_ctx->msg is set to NULL and then dereferenced
afterwards.  ecryptfs_send_raw_message() is the only place that
ecryptfs_send_miscdev() is called with data being NULL, but the only
caller of that function (ecryptfs_process_helo()) is never called.  In
short, there is currently no way to trigger the NULL pointer
dereference.

This patch removes the two unused functions and modifies
ecryptfs_send_miscdev() to remove the NULL dereferences.

Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

2 files changed, 11 insertions, 99 deletions

diff --git a/fs/ecryptfs/messaging.c b/fs/ecryptfs/messaging.c
index 295e7fa56755..f1c17e87c5fb 100644
--- a/fs/ecryptfs/messaging.c
+++ b/fs/ecryptfs/messaging.c
@@ -133,45 +133,6 @@ out:
         return rc;
 }
 
-static int
-ecryptfs_send_message_locked(char *data, int data_len, u8 msg_type,
-                             struct ecryptfs_msg_ctx **msg_ctx);
-
-/**
- * ecryptfs_send_raw_message
- * @msg_type: Message type
- * @daemon: Daemon struct for recipient of message
- *
- * A raw message is one that does not include an ecryptfs_message
- * struct. It simply has a type.
- *
- * Must be called with ecryptfs_daemon_hash_mux held.
- *
- * Returns zero on success; non-zero otherwise
- */
-static int ecryptfs_send_raw_message(u8 msg_type,
-                                     struct ecryptfs_daemon *daemon)
-{
-        struct ecryptfs_msg_ctx *msg_ctx;
-        int rc;
-
-        rc = ecryptfs_send_message_locked(NULL, 0, msg_type, &msg_ctx);
-        if (rc) {
-                printk(KERN_ERR "%s: Error whilst attempting to send "
-                       "message to ecryptfsd; rc = [%d]\n", __func__, rc);
-                goto out;
-        }
-        /* Raw messages are logically context-free (e.g., no
-         * reply is expected), so we set the state of the
-         * ecryptfs_msg_ctx object to indicate that it should
-         * be freed as soon as the message is sent. */
-        mutex_lock(&msg_ctx->mux);
-        msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_NO_REPLY;
-        mutex_unlock(&msg_ctx->mux);
-out:
-        return rc;
-}
-
 /**
  * ecryptfs_spawn_daemon - Create and initialize a new daemon struct
  * @daemon: Pointer to set to newly allocated daemon struct
@@ -212,49 +173,6 @@ out:
 }
 
 /**
- * ecryptfs_process_helo
- * @euid: The user ID owner of the message
- * @user_ns: The namespace in which @euid applies
- * @pid: The process ID for the userspace program that sent the
- *       message
- *
- * Adds the euid and pid values to the daemon euid hash.  If an euid
- * already has a daemon pid registered, the daemon will be
- * unregistered before the new daemon is put into the hash list.
- * Returns zero after adding a new daemon to the hash list;
- * non-zero otherwise.
- */
-int ecryptfs_process_helo(uid_t euid, struct user_namespace *user_ns,
-                          struct pid *pid)
-{
-        struct ecryptfs_daemon *new_daemon;
-        struct ecryptfs_daemon *old_daemon;
-        int rc;
-
-        mutex_lock(&ecryptfs_daemon_hash_mux);
-        rc = ecryptfs_find_daemon_by_euid(&old_daemon, euid, user_ns);
-        if (rc != 0) {
-                printk(KERN_WARNING "Received request from user [%d] "
-                       "to register daemon [0x%p]; unregistering daemon "
-                       "[0x%p]\n", euid, pid, old_daemon->pid);
-                rc = ecryptfs_send_raw_message(ECRYPTFS_MSG_QUIT, old_daemon);
-                if (rc)
-                        printk(KERN_WARNING "Failed to send QUIT "
-                               "message to daemon [0x%p]; rc = [%d]\n",
-                               old_daemon->pid, rc);
-                hlist_del(&old_daemon->euid_chain);
-                kfree(old_daemon);
-        }
-        rc = ecryptfs_spawn_daemon(&new_daemon, euid, user_ns, pid);
-        if (rc)
-                printk(KERN_ERR "%s: The gods are displeased with this attempt "
-                       "to create a new daemon object for euid [%d]; pid "
-                       "[0x%p]; rc = [%d]\n", __func__, euid, pid, rc);
-        mutex_unlock(&ecryptfs_daemon_hash_mux);
-        return rc;
-}
-
-/**
  * ecryptfs_exorcise_daemon - Destroy the daemon struct
  *
  * Must be called ceremoniously while in possession of
diff --git a/fs/ecryptfs/miscdev.c b/fs/ecryptfs/miscdev.c
index dda3c58eefc0..4ec8f61ccf5a 100644
--- a/fs/ecryptfs/miscdev.c
+++ b/fs/ecryptfs/miscdev.c
@@ -193,26 +193,20 @@ int ecryptfs_send_miscdev(char *data, size_t data_size,
         int rc = 0;
 
         mutex_lock(&msg_ctx->mux);
-        if (data) {
-                msg_ctx->msg = kmalloc((sizeof(*msg_ctx->msg) + data_size),
-                                       GFP_KERNEL);
-                if (!msg_ctx->msg) {
-                        rc = -ENOMEM;
-                        printk(KERN_ERR "%s: Out of memory whilst attempting "
-                               "to kmalloc(%zd, GFP_KERNEL)\n", __func__,
-                               (sizeof(*msg_ctx->msg) + data_size));
-                        goto out_unlock;
-                }
-        } else
-                msg_ctx->msg = NULL;
+        msg_ctx->msg = kmalloc((sizeof(*msg_ctx->msg) + data_size),
+                               GFP_KERNEL);
+        if (!msg_ctx->msg) {
+                rc = -ENOMEM;
+                printk(KERN_ERR "%s: Out of memory whilst attempting "
+                       "to kmalloc(%zd, GFP_KERNEL)\n", __func__,
+                       (sizeof(*msg_ctx->msg) + data_size));
+                goto out_unlock;
+        }
         msg_ctx->msg->index = msg_ctx->index;
         msg_ctx->msg->data_len = data_size;
         msg_ctx->type = msg_type;
-        if (data) {
-                memcpy(msg_ctx->msg->data, data, data_size);
-                msg_ctx->msg_size = (sizeof(*msg_ctx->msg) + data_size);
-        } else
-                msg_ctx->msg_size = 0;
+        memcpy(msg_ctx->msg->data, data, data_size);
+        msg_ctx->msg_size = (sizeof(*msg_ctx->msg) + data_size);
         mutex_lock(&daemon->mux);
         list_add_tail(&msg_ctx->daemon_out_list, &daemon->msg_ctx_out_queue);
         daemon->num_queued_msg_ctx++;