Re: [syzbot] [fs?] KASAN: slab-out-of-bounds Write in __put_unused_fd

[Hillf Danton]

On 12/31/24 2:27 PM, syzbot wrote:
> syzbot found the following issue on:
>
> HEAD commit:    8155b4ef3466 Add linux-next specific files for 20241220
> git tree:       linux-next
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13f42ac4580000

Test Eric's patch.

#syz test

--- x/fs/notify/fanotify/fanotify_user.c
+++ y/fs/notify/fanotify/fanotify_user.c
@@ -1624,8 +1624,8 @@ SYSCALL_DEFINE2(fanotify_init, unsigned
 	file = anon_inode_getfile_fmode("[fanotify]", &fanotify_fops, group,
 					f_flags, FMODE_NONOTIFY);
 	if (IS_ERR(file)) {
-		fd = PTR_ERR(file);
 		put_unused_fd(fd);
+		fd = PTR_ERR(file);
 		goto out_destroy_group;
 	}
 	fd_install(fd, file);
--