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>

1 files changed, 11 insertions, 17 deletions

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++;