ext2: introduce helper for xattr entry validation

Introduce helper function ext2_xattr_entry_valid()
for xattr entry validation and clean up the entry
check related code.

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Chengguang Xu <cgxu519@zoho.com.cn>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index db27260..fb2e008 100644 (file)
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -144,6 +144,22 @@ ext2_xattr_header_valid(struct ext2_xattr_header *header)
        return true;
 }
 
+static bool
+ext2_xattr_entry_valid(struct ext2_xattr_entry *entry, size_t end_offs)
+{
+       size_t size;
+
+       if (entry->e_value_block != 0)
+               return false;
+
+       size = le32_to_cpu(entry->e_value_size);
+       if (size > end_offs ||
+           le16_to_cpu(entry->e_value_offs) + size > end_offs)
+               return false;
+
+       return true;
+}
+
 /*
  * ext2_xattr_get()
  *
@@ -213,14 +229,10 @@ bad_block:
        error = -ENODATA;
        goto cleanup;
 found:
-       /* check the buffer size */
-       if (entry->e_value_block != 0)
-               goto bad_block;
-       size = le32_to_cpu(entry->e_value_size);
-       if (size > inode->i_sb->s_blocksize ||
-           le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize)
+       if (!ext2_xattr_entry_valid(entry, inode->i_sb->s_blocksize))
                goto bad_block;
 
+       size = le32_to_cpu(entry->e_value_size);
        if (ext2_xattr_cache_insert(ea_block_cache, bh))
                ea_idebug(inode, "cache insert failed");
        if (buffer) {
@@ -481,12 +493,10 @@ bad_block:
                if (flags & XATTR_CREATE)
                        goto cleanup;
                if (!here->e_value_block && here->e_value_size) {
-                       size_t size = le32_to_cpu(here->e_value_size);
-
-                       if (le16_to_cpu(here->e_value_offs) + size > 
-                           sb->s_blocksize || size > sb->s_blocksize)
+                       if (!ext2_xattr_entry_valid(here, sb->s_blocksize))
                                goto bad_block;
-                       free += EXT2_XATTR_SIZE(size);
+                       free += EXT2_XATTR_SIZE(
+                                       le32_to_cpu(here->e_value_size));
                }
                free += EXT2_XATTR_LEN(name_len);
        }