Re: [PATCH] cifs: initialize file_info_lock

[Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On Fri, 2017-01-13 at 15:00 +0100, Rabin Vincent wrote:
> From: Rabin Vincent <rabinv-VrBV9hrLPhE@public.gmane.org>
> 
> file_info_lock is not initalized in initiate_cifs_search(), leading to the
> following splat after a simple "mount.cifs ... dir && ls dir/":
> 
>  BUG: spinlock bad magic on CPU#0, ls/486
>   lock: 0xffff880009301110, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
>  CPU: 0 PID: 486 Comm: ls Not tainted 4.9.0 #27
>  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
>   ffffc900042f3db0 ffffffff81327533 0000000000000000 ffff880009301110
>   ffffc900042f3dd0 ffffffff810baf75 ffff880009301110 ffffffff817ae077
>   ffffc900042f3df0 ffffffff810baff6 ffff880009301110 ffff880008d69900
>  Call Trace:
>   [<ffffffff81327533>] dump_stack+0x65/0x92
>   [<ffffffff810baf75>] spin_dump+0x85/0xe0
>   [<ffffffff810baff6>] spin_bug+0x26/0x30
>   [<ffffffff810bb159>] do_raw_spin_lock+0xe9/0x130
>   [<ffffffff8159ad2f>] _raw_spin_lock+0x1f/0x30
>   [<ffffffff8127e50d>] cifs_closedir+0x4d/0x100
>   [<ffffffff81181cfd>] __fput+0x5d/0x160
>   [<ffffffff81181e3e>] ____fput+0xe/0x10
>   [<ffffffff8109410e>] task_work_run+0x7e/0xa0
>   [<ffffffff81002512>] exit_to_usermode_loop+0x92/0xa0
>   [<ffffffff810026f9>] syscall_return_slowpath+0x49/0x50
>   [<ffffffff8159b484>] entry_SYSCALL_64_fastpath+0xa7/0xa9
> 
> Fixes: 3afca265b5f53a0 ("Clarify locking of cifs file and tcon structures and make more granular")
> Signed-off-by: Rabin Vincent <rabinv-VrBV9hrLPhE@public.gmane.org>
> ---
>  fs/cifs/readdir.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
> index 8f6a2a5..a27fc87 100644
> --- a/fs/cifs/readdir.c
> +++ b/fs/cifs/readdir.c
> @@ -285,6 +285,7 @@ initiate_cifs_search(const unsigned int xid, struct file *file)
>  			rc = -ENOMEM;
>  			goto error_exit;
>  		}
> +		spin_lock_init(&cifsFile->file_info_lock);
>  		file->private_data = cifsFile;
>  		cifsFile->tlink = cifs_get_tlink(tlink);
>  		tcon = tlink_tcon(tlink);

Reviewed-by: Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>