ext4: add checks of block references for non-extent inodes

Check block references in the inode and indorect blocks for non-extent
inodes to make sure they are valid, and flag an error if they are
invalid.

Signed-off-by: Thiemo Nagel <thiemo.nagel@ph.tum.de>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 52 insertions, 7 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c7d9250fbc3..b3fd65d4650 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -371,6 +371,34 @@ static int ext4_block_to_path(struct inode *inode,
         return n;
 }
 
+static int __ext4_check_blockref(const char *function, struct inode *inode,
+                                 unsigned int *p, unsigned int max) {
+
+        unsigned int maxblocks = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es);
+        unsigned int *bref = p;
+        while (bref < p+max) {
+                if (unlikely(*bref >= maxblocks)) {
+                        ext4_error(inode->i_sb, function,
+                                   "block reference %u >= max (%u) "
+                                   "in inode #%lu, offset=%d",
+                                   *bref, maxblocks,
+                                   inode->i_ino, (int)(bref-p));
+                        return -EIO;
+                }
+                bref++;
+        }
+        return 0;
+}
+
+
+#define ext4_check_indirect_blockref(inode, bh)                         \
+        __ext4_check_blockref(__func__, inode, (__le32 *)(bh)->b_data,  \
+                              EXT4_ADDR_PER_BLOCK((inode)->i_sb))
+
+#define ext4_check_inode_blockref(inode)                                \
+        __ext4_check_blockref(__func__, inode, EXT4_I(inode)->i_data,   \
+                              EXT4_NDIR_BLOCKS)
+
 /**
  *      ext4_get_branch - read the chain of indirect blocks leading to data
  *      @inode: inode in question
@@ -415,9 +443,22 @@ static Indirect *ext4_get_branch(struct inode *inode, int depth,
         if (!p->key)
                 goto no_block;
         while (--depth) {
-                bh = sb_bread(sb, le32_to_cpu(p->key));
-                if (!bh)
+                bh = sb_getblk(sb, le32_to_cpu(p->key));
+                if (unlikely(!bh))
                         goto failure;
+                  
+                if (!bh_uptodate_or_lock(bh)) {
+                        if (bh_submit_read(bh) < 0) {
+                                put_bh(bh);
+                                goto failure;
+                        }
+                        /* validate block references */
+                        if (ext4_check_indirect_blockref(inode, bh)) {
+                                put_bh(bh);
+                                goto failure;
+                        }
+                }
+                
                 add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
                 /* Reader: end */
                 if (!p->key)
@@ -4371,11 +4412,15 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
         if (ei->i_flags & EXT4_EXTENTS_FL) {
                 /* Validate extent which is part of inode */
                 ret = ext4_ext_check_inode(inode);
-                if (ret) {
-                        brelse(bh);
-                        goto bad_inode;
-                }
-
+        } else if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
+                   (S_ISLNK(inode->i_mode) &&
+                    !ext4_inode_is_fast_symlink(inode))) {
+                /* Validate block references which are part of inode */
+                ret = ext4_check_inode_blockref(inode);
+        }
+        if (ret) {
+                brelse(bh);
+                goto bad_inode;
         }
 
         if (S_ISREG(inode->i_mode)) {