[PATCH] fs: Additional checks on new and old dir

[Edward Adam Davis <eadavis@qq.com>]

In the reproducer, when calling renameat2(), olddirfd and newdirfd passed
are the same value r0, see [1]. This situation should be avoided.

[1]
renameat2(r0, &(0x7f0000000240)='./bus/file0\x00', r0, &(0x7f00000001c0)='./file0\x00', 0x0)

Reported-by: syzbot+321477fad98ea6dd35b7@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=321477fad98ea6dd35b7
Tested-by: syzbot+321477fad98ea6dd35b7@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 fs/namei.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/namei.c b/fs/namei.c
index 84a0e0b0111c..ff843007ca94 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -5013,7 +5013,7 @@ int vfs_rename(struct renamedata *rd)
 	struct name_snapshot old_name;
 	bool lock_old_subdir, lock_new_subdir;
 
-	if (source == target)
+	if (source == target || old_dir == target)
 		return 0;
 
 	error = may_delete(rd->old_mnt_idmap, old_dir, old_dentry, is_dir);
-- 
2.43.0