ext4: store maxbytes for bitmapped files and return EFBIG as appropriate

Calculate & store the max offset for bitmapped files, and
catch too-large seeks, truncates, and writes in ext4, shortening
or rejecting as appropriate.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9cf85721d83c..eaace1373ccb 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -314,7 +314,10 @@ static int ext4_block_to_path(struct inode *inode,
                 offsets[n++] = i_block & (ptrs - 1);
                 final = ptrs;
         } else {
-                ext4_warning(inode->i_sb, "ext4_block_to_path", "block > big");
+                ext4_warning(inode->i_sb, "ext4_block_to_path",
+                                "block %u > max",
+                                i_block + direct_blocks +
+                                indirect_blocks + double_blocks);
         }
         if (boundary)
                 *boundary = final - 1 - (i_block & (ptrs - 1));
@@ -3092,6 +3095,17 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
                 ext4_journal_stop(handle);
         }
 
+        if (attr->ia_valid & ATTR_SIZE) {
+                if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
+                        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+
+                        if (attr->ia_size > sbi->s_bitmap_maxbytes) {
+                                error = -EFBIG;
+                                goto err_out;
+                        }
+                }
+        }
+
         if (S_ISREG(inode->i_mode) &&
             attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) {
                 handle_t *handle;