From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-180.mta1.migadu.com (out-180.mta1.migadu.com [95.215.58.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B7198314A8D for ; Fri, 24 Jul 2026 04:51:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784868707; cv=none; b=EVsbKQfssqLZrb1DYBrqxaiJ/q6vs6vZaNUsWIwa20KqW261m3nEbZk01EY37YKn3Xs8VPunQXPgQQ76QhvsWEnVb8nyQd/IStqFnvjk5OnLj/QE8MxPir/9UxA+JRoLG9fmvr+vbvbkw4AdqDucvVLdYvizXY2Q7f8rx5Ep1eI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784868707; c=relaxed/simple; bh=l3uotQg+BF6am/nT/S2L1dXBa9p5sUXNXnqDlwrBIQ8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=iU/lbV9DMby/T7pAd4iggAik/b6tXsBceBpOGE3p0jE+8aNtPmTXVxX/jjy6Ig396buy1y2gpCeRiH8KL+QBDCO8vr8OQ1vK7EXFuGJensbnA6kFKwymyaEsIHeX62TnrC2EgEJ49audJc07hOJyrC+7ZQHqe6GyDbTBGy8iLmI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=chenxiaosong.com; spf=pass smtp.mailfrom=chenxiaosong.com; dkim=pass (2048-bit key) header.d=chenxiaosong.com header.i=@chenxiaosong.com header.b=q8MlsSKf; arc=none smtp.client-ip=95.215.58.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=chenxiaosong.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chenxiaosong.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=chenxiaosong.com header.i=@chenxiaosong.com header.b="q8MlsSKf" Message-ID: <09e27951-06a6-4dc7-bc44-cf9eff87d271@chenxiaosong.com> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chenxiaosong.com; s=key1; t=1784868701; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4Iva+/lDdfBysQhNAXJZV/BkE1gNWZl/90SRLyCVwoc=; b=q8MlsSKf5ocbletV1lNR2YQL8PnpQze/urm5UudY7cehS0fvu+/D7i4bbkpZ3mKQI5txEc W9FJmEtueJTznsVAT46fsbRgidKyI0vrNI3z1U1BRN2/IVxx1WHa1txUxziHI23ki6VuXe PZia5COGCBkZS8JENxq5+dpJwHG5xrpIaImrUUs/O6vGmrm/k/6nRofAW7Ssw/Vps3mayi P/7nbkulUXEnZ8lzvi1w8fw6zvdrRp1kkQIVuuZD4E9wFLNbvS4a/XEimdFJ9Bg681IWyp q4mBZFHuV1HGDVgzgtNg4dzlIez0pxuU/sY2DyZsxvBR3FFJ1zh22Vb9/h/Q2g== Date: Fri, 24 Jul 2026 12:51:14 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH] ksmbd: only rebind the reopened file's own oplock on durable reconnect To: Your Name , linux-cifs@vger.kernel.org Cc: linkinjeon@kernel.org, smfrench@gmail.com, senozhatsky@chromium.org, tom@talpey.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260723230053.684176-1-you@example.com> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: ChenXiaoSong In-Reply-To: <20260723230053.684176-1-you@example.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT Reviewed-by: ChenXiaoSong By the way, your email signature is "Your Name". Did you forget to set your name in .gitconfig? On 7/24/26 07:00, Your Name wrote: > From: Aldo Ariel Panzardo > > ksmbd_reopen_durable_fd() walks the inode's m_op_list and rebinds every > detached oplock to the reconnecting session: > > list_for_each_entry_rcu(op, &ci->m_op_list, op_entry, > lockdep_is_held(&ci->m_lock)) { > if (op->conn) > continue; > op->conn = ksmbd_conn_get(fp->conn); > op->sess = work->sess; > } > > The only key is op->conn == NULL, which every detached durable handle on > that inode matches, not just the one owned by fp. When two sessions hold > durable handles on the same file and both disconnect, reconnecting one of > them adopts the other session's oplock: op->sess is overwritten with the > reconnecting session without taking a reference on it, while op->conn > pins the connection. > > The sibling teardown path, session_fd_check(), keys on the identity of > the connection being torn down (op->conn == conn) rather than on shared > state, and so does not have this problem. > > Once the adopting session is destroyed, ksmbd_session_destroy() frees it > while the foreign oplock still points at it. The reader in > ksmbd_close_fd_app_instance_id() validates only opinfo->conn, which is > still live thanks to the reference taken above, and then dereferences the > stale session: > > if (!opinfo->conn) { > up_read(&fp->f_ci->m_lock); > goto out; > } > > ft = &opinfo->sess->file_table; > write_lock(&ft->lock); > > BUG: KASAN: slab-use-after-free in _raw_write_lock+0x74/0xd0 > Write of size 4 at addr ffff88810a970528 by task kworker/0:0/9 > Workqueue: ksmbd-io handle_ksmbd_work > Call Trace: > _raw_write_lock+0x74/0xd0 > ksmbd_close_fd_app_instance_id+0x183/0x410 > smb2_open+0x1346/0x4430 > handle_ksmbd_work+0x2bb/0x7b0 > > Reached from an authenticated session against a share with the default > durable-handle and oplock configuration: two sessions open the same file > with a durable-v2 handle and an RH lease under distinct AppInstanceIds, > both log off, one reconnects with DH2C, and a later durable-v2 create > carrying the other AppInstanceId walks into the freed session. > > Constrain the loop to the oplock owned by the file being reopened. > > Fixes: f363a0fb134a ("ksmbd: fix app-instance durable supersede session UAF") > Cc: stable@vger.kernel.org > Signed-off-by: Aldo Ariel Panzardo > --- > fs/smb/server/vfs_cache.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/smb/server/vfs_cache.c b/fs/smb/server/vfs_cache.c > index d95c405eab11..1e9d13344825 100644 > --- a/fs/smb/server/vfs_cache.c > +++ b/fs/smb/server/vfs_cache.c > @@ -1720,7 +1720,7 @@ int ksmbd_reopen_durable_fd(struct ksmbd_work *work, struct ksmbd_file *fp) > down_write(&ci->m_lock); > list_for_each_entry_rcu(op, &ci->m_op_list, op_entry, > lockdep_is_held(&ci->m_lock)) { > - if (op->conn) > + if (op->conn || op->o_fp != fp) > continue; > op->conn = ksmbd_conn_get(fp->conn); > op->sess = work->sess; -- ChenXiaoSong Chinese Homepage: https://chenxiaosong.com English Homepage: https://chenxiaosong.com/en