Commit 728d392f authored by Javier Pello's avatar Javier Pello Committed by Jan Kara
Browse files

fs/ext2: Avoid page_address on pages returned by ext2_get_page 

Commit 782b76d7 ("fs/ext2: Replace
kmap() with kmap_local_page()") replaced the kmap/kunmap calls in
ext2_get_page/ext2_put_page with kmap_local_page/kunmap_local for
efficiency reasons. As a necessary side change, the commit also
made ext2_get_page (and ext2_find_entry and ext2_dotdot) return
the mapping address along with the page itself, as it is required
for kunmap_local, and converted uses of page_address on such pages
to use the newly returned address instead. However, uses of
page_address on such pages were missed in ext2_check_page and
ext2_delete_entry, which triggers oopses if kmap_local_page happens
to return an address from high memory. Fix this now by converting
the remaining uses of page_address to use the right address, as
returned by kmap_local_page.

Link: https://lore.kernel.org/r/20210714185448.8707ac239e9f12b3a7f5b9f9@urjc.es


Reviewed-by: default avatarIra Weiny <ira.weiny@intel.com>
Signed-off-by: default avatarJavier Pello <javier.pello@urjc.es>
Fixes: 782b76d7 ("fs/ext2: Replace kmap() with kmap_local_page()")
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 2acf15b9

fs/ext2/dir.c

+6 −6
Original line number Diff line number Diff line
@@ -106,12 +106,11 @@ static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len) 
	return err;

}



static bool ext2_check_page(struct page *page, int quiet)

static bool ext2_check_page(struct page *page, int quiet, char *kaddr)

{

	struct inode *dir = page->mapping->host;

	struct super_block *sb = dir->i_sb;

	unsigned chunk_size = ext2_chunk_size(dir);

	char *kaddr = page_address(page);

	u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);

	unsigned offs, rec_len;

	unsigned limit = PAGE_SIZE;
@@ -205,7 +204,8 @@ static struct page * ext2_get_page(struct inode *dir, unsigned long n, 
	if (!IS_ERR(page)) {

		*page_addr = kmap_local_page(page);

		if (unlikely(!PageChecked(page))) {

			if (PageError(page) || !ext2_check_page(page, quiet))

			if (PageError(page) || !ext2_check_page(page, quiet,

								*page_addr))

				goto fail;

		}

	}
@@ -584,10 +584,10 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode) 
 * ext2_delete_entry deletes a directory entry by merging it with the

 * previous entry. Page is up-to-date.

 */

int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )

int ext2_delete_entry (struct ext2_dir_entry_2 *dir, struct page *page,

			char *kaddr)

{

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

	char *kaddr = page_address(page);

	unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);

	unsigned to = ((char *)dir - kaddr) +

				ext2_rec_len_from_disk(dir->rec_len);
@@ -607,7 +607,7 @@ int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page ) 
		de = ext2_next_entry(de);

	}

	if (pde)

		from = (char*)pde - (char*)page_address(page);

		from = (char *)pde - kaddr;

	pos = page_offset(page) + from;

	lock_page(page);

	err = ext2_prepare_chunk(page, pos, to - from);

fs/ext2/ext2.h

+2 −1
Original line number Diff line number Diff line
@@ -740,7 +740,8 @@ extern int ext2_inode_by_name(struct inode *dir, 
extern int ext2_make_empty(struct inode *, struct inode *);

extern struct ext2_dir_entry_2 *ext2_find_entry(struct inode *, const struct qstr *,

						struct page **, void **res_page_addr);

extern int ext2_delete_entry (struct ext2_dir_entry_2 *, struct page *);

extern int ext2_delete_entry(struct ext2_dir_entry_2 *dir, struct page *page,

			     char *kaddr);

extern int ext2_empty_dir (struct inode *);

extern struct ext2_dir_entry_2 *ext2_dotdot(struct inode *dir, struct page **p, void **pa);

extern void ext2_set_link(struct inode *, struct ext2_dir_entry_2 *, struct page *, void *,

fs/ext2/namei.c

+2 −2
Original line number Diff line number Diff line
@@ -293,7 +293,7 @@ static int ext2_unlink(struct inode * dir, struct dentry *dentry) 
		goto out;

	}



	err = ext2_delete_entry (de, page);

	err = ext2_delete_entry (de, page, page_addr);

	ext2_put_page(page, page_addr);

	if (err)

		goto out;
@@ -397,7 +397,7 @@ static int ext2_rename (struct user_namespace * mnt_userns, 
	old_inode->i_ctime = current_time(old_inode);

	mark_inode_dirty(old_inode);



	ext2_delete_entry(old_de, old_page);

	ext2_delete_entry(old_de, old_page, old_page_addr);



	if (dir_de) {

		if (old_dir != new_dir)