ocfs2: Check xattr block signatures properly.

The xattr.c code is currently memcmp()ing naking buffer pointers.
Create the OCFS2_IS_VALID_XATTR_BLOCK() macro to match its peers and use
that.

In addition, failed signature checks were returning -EFAULT, which is
completely wrong.  Return -EIO.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

2 files changed, 19 insertions, 22 deletions

diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index a21a465490c4..fef7ece32376 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -473,6 +473,9 @@ static inline int ocfs2_uses_extended_slot_map(struct ocfs2_super *osb)
                 (____gd)->bg_signature);                                \
 } while (0)
 
+#define OCFS2_IS_VALID_XATTR_BLOCK(ptr)                                 \
+        (!strcmp((ptr)->xb_signature, OCFS2_XATTR_BLOCK_SIGNATURE))
+
 static inline unsigned long ino_from_blkno(struct super_block *sb,
                                            u64 blkno)
 {
diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index e19980a71a3c..151ba6257fbb 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -555,14 +555,12 @@ static int ocfs2_xattr_block_list(struct inode *inode,
                 mlog_errno(ret);
                 return ret;
         }
-        /*Verify the signature of xattr block*/
-        if (memcmp((void *)blk_bh->b_data, OCFS2_XATTR_BLOCK_SIGNATURE,
-                   strlen(OCFS2_XATTR_BLOCK_SIGNATURE))) {
-                ret = -EFAULT;
-                goto cleanup;
-        }
 
         xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
+        if (!OCFS2_IS_VALID_XATTR_BLOCK(xb)) {
+                ret = -EIO;
+                goto cleanup;
+        }
 
         if (!(le16_to_cpu(xb->xb_flags) & OCFS2_XATTR_INDEXED)) {
                 struct ocfs2_xattr_header *header = &xb->xb_attrs.xb_header;
@@ -779,15 +777,14 @@ static int ocfs2_xattr_block_get(struct inode *inode,
                 mlog_errno(ret);
                 return ret;
         }
-        /*Verify the signature of xattr block*/
-        if (memcmp((void *)blk_bh->b_data, OCFS2_XATTR_BLOCK_SIGNATURE,
-                   strlen(OCFS2_XATTR_BLOCK_SIGNATURE))) {
-                ret = -EFAULT;
+
+        xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
+        if (!OCFS2_IS_VALID_XATTR_BLOCK(xb)) {
+                ret = -EIO;
                 goto cleanup;
         }
 
         xs->xattr_bh = blk_bh;
-        xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
 
         if (!(le16_to_cpu(xb->xb_flags) & OCFS2_XATTR_INDEXED)) {
                 xs->header = &xb->xb_attrs.xb_header;
@@ -1527,10 +1524,9 @@ static int ocfs2_xattr_free_block(struct inode *inode,
                 goto out;
         }
 
-        /*Verify the signature of xattr block*/
-        if (memcmp((void *)blk_bh->b_data, OCFS2_XATTR_BLOCK_SIGNATURE,
-                   strlen(OCFS2_XATTR_BLOCK_SIGNATURE))) {
-                ret = -EFAULT;
+        xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
+        if (!OCFS2_IS_VALID_XATTR_BLOCK(xb)) {
+                ret = -EIO;
                 goto out;
         }
 
@@ -1540,7 +1536,6 @@ static int ocfs2_xattr_free_block(struct inode *inode,
                 goto out;
         }
 
-        xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
         blk = le64_to_cpu(xb->xb_blkno);
         bit = le16_to_cpu(xb->xb_suballoc_bit);
         bg_blkno = ocfs2_which_suballoc_group(blk, bit);
@@ -1784,15 +1779,14 @@ static int ocfs2_xattr_block_find(struct inode *inode,
                 mlog_errno(ret);
                 return ret;
         }
-        /*Verify the signature of xattr block*/
-        if (memcmp((void *)blk_bh->b_data, OCFS2_XATTR_BLOCK_SIGNATURE,
-                   strlen(OCFS2_XATTR_BLOCK_SIGNATURE))) {
-                        ret = -EFAULT;
-                        goto cleanup;
+
+        xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
+        if (!OCFS2_IS_VALID_XATTR_BLOCK(xb)) {
+                ret = -EIO;
+                goto cleanup;
         }
 
         xs->xattr_bh = blk_bh;
-        xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
 
         if (!(le16_to_cpu(xb->xb_flags) & OCFS2_XATTR_INDEXED)) {
                 xs->header = &xb->xb_attrs.xb_header;