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    DateThu, 21 Dec 2006 12:58:28 -0600
    FromEric Sandeen <>
    Subject[PATCH] ext2: skip pages past number of blocks in ext2_find_entry
    This one was pointed out on the MOKB site:
    http://kernelfun.blogspot.com/2006/11/mokb-09-11-2006-linux-26x-ext2checkpage.html
    
    If a directory's i_size is corrupted, ext2_find_entry() will keep processing
    pages until the i_size is reached, even if there are no more blocks associated
    with the directory inode.  This patch puts in some minimal sanity-checking
    so that we don't keep checking pages (and issuing errors) if we know there
    can be no more data to read, based on the block count of the directory inode.
    
    This is somewhat similar in approach to the ext3 patch I sent earlier this
    year.
    
    Thanks,
    
    -Eric
    
    Signed-off-by: Eric Sandeen <sandeen@redhat.com>
    
    Index: linux-2.6.19/fs/ext2/dir.c
    ===================================================================
    --- linux-2.6.19.orig/fs/ext2/dir.c
    +++ linux-2.6.19/fs/ext2/dir.c
    @@ -368,6 +368,14 @@ struct ext2_dir_entry_2 * ext2_find_entr
     		}
     		if (++n >= npages)
     			n = 0;
    +		/* next page is past the blocks we've got */
    +		if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
    +			ext2_error(dir->i_sb, __FUNCTION__,
    +				"dir %lu size %lld exceeds block count %llu",
    +				dir->i_ino, dir->i_size,
    +				(unsigned long long)dir->i_blocks);
    +				goto out;
    +		}
     	} while (n != start);
     out:
     	return NULL;
    
    -
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