fs/ext2: Avoid page_address on pages returned by ext2_get_page

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>

diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index 14292db..2c2f179 100644 (file)
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -106,12 +106,11 @@ static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
        return err;
 }
 
        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);
 {
        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;
        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 (!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;
                }
        }
                                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.
  */
  * 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;
 {
        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);
        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)
                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);
        pos = page_offset(page) + from;
        lock_page(page);
        err = ext2_prepare_chunk(page, pos, to - from);

diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index b0a6948..e512630 100644 (file)
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -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_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 *,
 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 *,

diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index 1f69b81..5f6b756 100644 (file)
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -293,7 +293,7 @@ static int ext2_unlink(struct inode * dir, struct dentry *dentry)
                goto out;
        }
 
                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;
        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);
 
        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)
 
        if (dir_de) {
                if (old_dir != new_dir)