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hfsplus: fix oops on mount with corrupted btree extent records 

A particular fsfuzzer run caused an hfs file system to crash on mount. This
is due to a corrupted MDB extent record causing a miscalculation of
HFSPLUS_I(inode)->first_blocks for the extent tree. If the extent records
are zereod out, then it won't trigger the first_blocks special case and
instead falls through to the extent code, which we're in the middle
of initializing.

This patch catches the 0 size extent records, reports the corruption,
and fails the mount.

[hch: ported of commit 47f365eb57 from hfs]

Reported-by: Ramon de Carvalho Valle <rcvalle@linux.vnet.ibm.com>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Christoph Hellwig <hch@tuxera.com>
This commit is contained in:
Jeff Mahoney 2010-10-14 09:53:37 -04:00 committed by Christoph Hellwig
parent 40de9a7ceb
commit ee52716245
1 changed files with 9 additions and 2 deletions
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11
fs/hfsplus/btree.c
View File

@ -39,10 +39,16 @@ struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id)
goto free_tree;
tree->inode = inode;
if (!HFSPLUS_I(tree->inode)->first_blocks) {
printk(KERN_ERR
"hfs: invalid btree extent records (0 size).\n");
goto free_inode;
}
mapping = tree->inode->i_mapping;
page = read_mapping_page(mapping, 0, NULL);
if (IS_ERR(page))
goto free_tree;
goto free_inode;
/* Load the header */
head = (struct hfs_btree_header_rec *)(kmap(page) + sizeof(struct hfs_bnode_desc));
@ -89,8 +95,9 @@ struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id)
fail_page:
tree->inode->i_mapping->a_ops = &hfsplus_aops;
page_cache_release(page);
free_tree:
free_inode:
iput(tree->inode);
free_tree:
kfree(tree);
return NULL;
}