Commit 102e57d5 authored by Jan Kara's avatar Jan Kara
Browse files

udf: Fix race between file type conversion and writeback 



udf_setsize() can race with udf_writepages() as follows:

udf_setsize()			udf_writepages()
				  if (iinfo->i_alloc_type ==
						ICBTAG_FLAG_AD_IN_ICB)
  err = udf_expand_file_adinicb(inode);
  err = udf_extend_file(inode, newsize);
				    udf_adinicb_writepages()
				      memcpy_from_file_folio() - crash
					because inode size is too big.

Fix the problem by checking the file type under folio lock in
udf_handle_page_wb() handler called from __mpage_writepages() which
properly serializes with udf_expand_file_adinicb().

Reported-by: default avatarJianzhou Zhao <luckd0g@163.com>
Link: https://lore.kernel.org/all/f622c01.67ac.19cdbdd777d.Coremail.luckd0g@163.com


Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260326140635.15895-4-jack@suse.cz


Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent fffca572

fs/udf/inode.c

+15 −18
Original line number Diff line number Diff line
@@ -181,22 +181,23 @@ static void udf_write_failed(struct address_space *mapping, loff_t to) 
	}

}



static int udf_adinicb_writepages(struct address_space *mapping,

static int udf_handle_page_wb(struct folio *folio,

			      struct writeback_control *wbc)

{

	struct inode *inode = mapping->host;

	struct inode *inode = folio->mapping->host;

	struct udf_inode_info *iinfo = UDF_I(inode);

	struct folio *folio = NULL;

	int error = 0;



	while ((folio = writeback_iter(mapping, wbc, folio, &error))) {

		BUG_ON(!folio_test_locked(folio));

		BUG_ON(folio->index != 0);

	/*

	 * Inodes in the normal format are handled by the generic code. This

	 * check is race-free as the folio lock protects us from inode type

	 * conversion.

	 */

	if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB)

		return 1;



	memcpy_from_file_folio(iinfo->i_data + iinfo->i_lenEAttr, folio,

				0, i_size_read(inode));

	folio_unlock(folio);

	}



	mark_inode_dirty(inode);

	return 0;

}
@@ -204,12 +205,8 @@ static int udf_adinicb_writepages(struct address_space *mapping, 
static int udf_writepages(struct address_space *mapping,

			  struct writeback_control *wbc)

{

	struct inode *inode = mapping->host;

	struct udf_inode_info *iinfo = UDF_I(inode);



	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB)

		return udf_adinicb_writepages(mapping, wbc);

	return mpage_writepages(mapping, wbc, udf_get_block_wb);

	return __mpage_writepages(mapping, wbc, udf_get_block_wb,

				  udf_handle_page_wb);

}



static void udf_adinicb_read_folio(struct folio *folio)