ecryptfs: fix memory corruption when storing crypto info in xattrs

[linux-2.6-omap-h63xx.git] / fs / ecryptfs / crypto.c

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 06db79d05c1262a8de76fc9dcb820b910b464163..6046239465a147f28a8227ae075472c3bafd2757 100644 (file)
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1251,6 +1251,7 @@ struct kmem_cache *ecryptfs_header_cache_2;
 /**
  * ecryptfs_write_headers_virt
  * @page_virt: The virtual address to write the headers to
+ * @max: The size of memory allocated at page_virt
  * @size: Set to the number of bytes written by this function
  * @crypt_stat: The cryptographic context
  * @ecryptfs_dentry: The eCryptfs dentry
@@ -1278,7 +1279,8 @@ struct kmem_cache *ecryptfs_header_cache_2;
  *
  * Returns zero on success
  */
-static int ecryptfs_write_headers_virt(char *page_virt, size_t *size,
+static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
+                                      size_t *size,
                                       struct ecryptfs_crypt_stat *crypt_stat,
                                       struct dentry *ecryptfs_dentry)
 {
@@ -1296,7 +1298,7 @@ static int ecryptfs_write_headers_virt(char *page_virt, size_t *size,
        offset += written;
        rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
                                              ecryptfs_dentry, &written,
-                                             PAGE_CACHE_SIZE - offset);
+                                             max - offset);
        if (rc)
                ecryptfs_printk(KERN_WARNING, "Error generating key packet "
                                "set; rc = [%d]\n", rc);
@@ -1368,14 +1370,14 @@ int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry)
                goto out;
        }
        /* Released in this function */
-       virt = kzalloc(crypt_stat->num_header_bytes_at_front, GFP_KERNEL);
+       virt = (char *)get_zeroed_page(GFP_KERNEL);
        if (!virt) {
                printk(KERN_ERR "%s: Out of memory\n", __func__);
                rc = -ENOMEM;
                goto out;
        }
-       rc = ecryptfs_write_headers_virt(virt, &size, crypt_stat,
-                                        ecryptfs_dentry);
+       rc = ecryptfs_write_headers_virt(virt, PAGE_CACHE_SIZE, &size,
+                                        crypt_stat, ecryptfs_dentry);
        if (unlikely(rc)) {
                printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
                       __func__, rc);
@@ -1393,8 +1395,7 @@ int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry)
                goto out_free;
        }
 out_free:
-       memset(virt, 0, crypt_stat->num_header_bytes_at_front);
-       kfree(virt);
+       free_page((unsigned long)virt);
 out:
        return rc;
 }