[PATCH 5.13 002/104] fs/ext2: Avoid page_address on pages returned by ext2_get_page

Greg Kroah-Hartman
2021-08-02T14:05:02Z

From: Javier Pello <javier.pello@urjc.es>

commit 728d392f8a799f037812d0f2b254fb3b5e115fcf upstream.

Commit 782b76d7abdf02b12c46ed6f1e9bf715569027f7 ("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: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Javier Pello <javier.pello@urjc.es>
Fixes: 782b76d7abdf ("fs/ext2: Replace kmap() with kmap_local_page()")
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ext2/dir.c | 12 ++++++------
fs/ext2/ext2.h | 3 ++-
fs/ext2/namei.c | 4 ++--
3 files changed, 10 insertions(+), 9 deletions(-)

--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -106,12 +106,11 @@ static int ext2_commit_chunk(struct page
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(struc
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 @@ out_unlock:
* 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_e
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);
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -740,7 +740,8 @@ extern int ext2_inode_by_name(struct ino
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 *,
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -293,7 +293,7 @@ static int ext2_unlink(struct inode * di
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_name
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)