fs: hfsplus: fix UAF issue in hfsplus_put_super

The current hfsplus_put_super first calls hfs_btree_close on
sbi->ext_tree, then invokes iput on sbi->hidden_dir, resulting in an
use-after-free issue in hfsplus_release_folio.

As shown in hfsplus_fill_super, the error handling code also calls iput
before hfs_btree_close.

To fix this error, we move all iput calls before hfsplus_btree_close.

Note that this patch is tested on Syzbot.

Link: https://lkml.kernel.org/r/20230226124948.3175736-1-mudongliangabcd@gmail.com
Reported-by: syzbot+57e3e98f7e3b80f64d56@syzkaller.appspotmail.com
Tested-by: Dongliang Mu <mudongliangabcd@gmail.com>
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/hfsplus/super.c b/fs/hfsplus/super.c
index 122ed89..1986b4f 100644 (file)
--- a/fs/hfsplus/super.c
+++ b/fs/hfsplus/super.c
@@ -295,11 +295,11 @@ static void hfsplus_put_super(struct super_block *sb)
                hfsplus_sync_fs(sb, 1);
        }
 
+       iput(sbi->alloc_file);
+       iput(sbi->hidden_dir);
        hfs_btree_close(sbi->attr_tree);
        hfs_btree_close(sbi->cat_tree);
        hfs_btree_close(sbi->ext_tree);
-       iput(sbi->alloc_file);
-       iput(sbi->hidden_dir);
        kfree(sbi->s_vhdr_buf);
        kfree(sbi->s_backup_vhdr_buf);
        unload_nls(sbi->nls);