From: Simon Gander simon@tuxera.com Subject: hfsplus: fix crash and filesystem corruption when deleting files

When removing files containing extended attributes, the hfsplus driver may remove the wrong entries from the attributes b-tree, causing major filesystem damage and in some cases even kernel crashes.

To remove a file, all its extended attributes have to be removed as well. The driver does this by looking up all keys in the attributes b-tree with the cnid of the file. Each of these entries then gets deleted using the key used for searching, which doesn't contain the attribute's name when it should. Since the key doesn't contain the name, the deletion routine will not find the correct entry and instead remove the one in front of it. If parent nodes have to be modified, these become corrupt as well. This causes invalid links and unsorted entries that not even macOS's fsck_hfs is able to fix.

To fix this, modify the search key before an entry is deleted from the attributes b-tree by copying the found entry's key into the search key, therefore ensuring that the correct entry gets removed from the tree.

Link: http://lkml.kernel.org/r/20200327155541.1521-1-simon@tuxera.com Signed-off-by: Simon Gander simon@tuxera.com Reviewed-by: Anton Altaparmakov anton@tuxera.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/hfsplus/attributes.c | 4 ++++ 1 file changed, 4 insertions(+)

--- a/fs/hfsplus/attributes.c~hfsplus-fix-crash-and-filesystem-corruption-when-deleting-files +++ a/fs/hfsplus/attributes.c @@ -292,6 +292,10 @@ static int __hfsplus_delete_attr(struct return -ENOENT; }

+ /* Avoid btree corruption */ + hfs_bnode_read(fd->bnode, fd->search_key, + fd->keyoffset, fd->keylength); + err = hfs_brec_remove(fd); if (err) return err; _