ext4: clean up ext4_xattr_inode_get()

The input and output values of *size parameter are equal on successful
return from ext4_xattr_inode_get().  On error return, the callers ignore
the output value so there is no need to update it.

Also check for NULL return from ext4_bread().  If the actual xattr inode
size happens to be smaller than the expected size, ext4_bread() may
return NULL which would indicate data corruption.

Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 13 insertions, 22 deletions

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index f16a90824d44..61c67a04a7e1 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -278,37 +278,28 @@ ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
 /*
  * Read the EA value from an inode.
  */
-static int
-ext4_xattr_inode_read(struct inode *ea_inode, void *buf, size_t *size)
+static int ext4_xattr_inode_read(struct inode *ea_inode, void *buf, size_t size)
 {
         unsigned long block = 0;
         struct buffer_head *bh = NULL;
-        int blocksize;
-        size_t csize, ret_size = 0;
-
-        if (*size == 0)
-                return 0;
+        int blocksize = ea_inode->i_sb->s_blocksize;
+        size_t csize, copied = 0;
 
-        blocksize = ea_inode->i_sb->s_blocksize;
-
-        while (ret_size < *size) {
-                csize = (*size - ret_size) > blocksize ? blocksize :
-                                                        *size - ret_size;
+        while (copied < size) {
+                csize = (size - copied) > blocksize ? blocksize : size - copied;
                 bh = ext4_bread(NULL, ea_inode, block, 0);
-                if (IS_ERR(bh)) {
-                        *size = ret_size;
+                if (IS_ERR(bh))
                         return PTR_ERR(bh);
-                }
+                if (!bh)
+                        return -EFSCORRUPTED;
+
                 memcpy(buf, bh->b_data, csize);
                 brelse(bh);
 
                 buf += csize;
                 block += 1;
-                ret_size += csize;
+                copied += csize;
         }
-
-        *size = ret_size;
-
         return 0;
 }
 
@@ -360,7 +351,7 @@ error:
  */
 static int
 ext4_xattr_inode_get(struct inode *inode, unsigned long ea_ino, void *buffer,
-                     size_t *size)
+                     size_t size)
 {
         struct inode *ea_inode;
         int ret;
@@ -417,7 +408,7 @@ ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
                 if (entry->e_value_inum) {
                         error = ext4_xattr_inode_get(inode,
                                              le32_to_cpu(entry->e_value_inum),
-                                             buffer, &size);
+                                             buffer, size);
                         if (error)
                                 goto cleanup;
                 } else {
@@ -467,7 +458,7 @@ ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
                 if (entry->e_value_inum) {
                         error = ext4_xattr_inode_get(inode,
                                              le32_to_cpu(entry->e_value_inum),
-                                             buffer, &size);
+                                             buffer, size);
                         if (error)
                                 goto cleanup;
                 } else {