From: Li Guifu <bluce.liguifu@huawei.com>
Date: Fri, 24 Jul 2020 01:38:11 +0000 (+0800)
Subject: f2fs: fix use-after-free issue
X-Git-Tag: v5.9-rc1~69^2~12
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=99c787cfd2bd04926f1f553b30bd7dcea2caaba1;p=thirdparty%2Fkernel%2Flinux.git

f2fs: fix use-after-free issue

During umount, f2fs_put_super() unregisters procfs entries after
f2fs_destroy_segment_manager(), it may cause use-after-free
issue when umount races with procfs accessing, fix it by relocating
f2fs_unregister_sysfs().

[Chao Yu: change commit title/message a bit]

Signed-off-by: Li Guifu <bluce.liguifu@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 80cb7cd358f84..5e0a3eeb8ca46 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1175,6 +1175,9 @@ static void f2fs_put_super(struct super_block *sb)
 	int i;
 	bool dropped;
 
+	/* unregister procfs/sysfs entries in advance to avoid race case */
+	f2fs_unregister_sysfs(sbi);
+
 	f2fs_quota_off_umount(sb);
 
 	/* prevent remaining shrinker jobs */
@@ -1240,8 +1243,6 @@ static void f2fs_put_super(struct super_block *sb)
 
 	kvfree(sbi->ckpt);
 
-	f2fs_unregister_sysfs(sbi);
-
 	sb->s_fs_info = NULL;
 	if (sbi->s_chksum_driver)
 		crypto_free_shash(sbi->s_chksum_driver);