From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 DA40735B158; Fri, 9 Jan 2026 12:36:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767962188; cv=none; b=Ci6p0bVOw9K2LKi+wEyM2exdNmHtbG9rTphBgzkB7r1XrmoZDCxb/pFxvQkAp02ozr3hR5iZKzDfHfEHaMoqPA1ITkNTc1+LA4e/oXGVsS2ZIlcusfcVjON5HAnauylTjUXs0LLewAFgxyy2GwfvLJ3xkBj5txxK4017S3Xupn4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767962188; c=relaxed/simple; bh=H+ZfWNowBp+x7/SqDlLG8E8a4/ZEOPg/gt3O0fuPeRM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OMDsae5eQY4u3ULxgRmlt8KK4TdQ9VJU6WcCXW7NAH1QMKRJogiyHG3sQBolpXhFcJWNXusibUvKkUNGm8rB9Zi9pk81bqCUDMA0qZ89CL9M0qQLkRAuHItxCFGG4FbFijx+4gcMus66chX8cj7dkfOL0btkLTfaAFZ15Ibwgqk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=i3HZQwhm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="i3HZQwhm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6872AC19422; Fri, 9 Jan 2026 12:36:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767962188; bh=H+ZfWNowBp+x7/SqDlLG8E8a4/ZEOPg/gt3O0fuPeRM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=i3HZQwhmeTtyf1OOPMPRXMhK3fIO+sXjXYDs+ZgB0VSUp0KGyAEP9gHD7XLjmE+kR TEBGh/kjZi25rv7taDpyYai4QslR4D37n5GHnK1K3Ozd1KPu6lhbomJwHjZdsqz96b Bu52jZkvVF9kPWB9ptDV6l5u4un5kDbLIeNV37dw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Qianchang Zhao , Zhitong Liu , Namjae Jeon , Steve French , Sasha Levin Subject: [PATCH 6.1 245/634] ksmbd: fix use-after-free in ksmbd_tree_connect_put under concurrency Date: Fri, 9 Jan 2026 12:38:43 +0100 Message-ID: <20260109112126.760866222@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260109112117.407257400@linuxfoundation.org> References: <20260109112117.407257400@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Namjae Jeon [ Upstream commit b39a1833cc4a2755b02603eec3a71a85e9dff926 ] Under high concurrency, A tree-connection object (tcon) is freed on a disconnect path while another path still holds a reference and later executes *_put()/write on it. Reported-by: Qianchang Zhao Reported-by: Zhitong Liu Signed-off-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin --- fs/smb/server/mgmt/tree_connect.c | 18 ++++-------------- fs/smb/server/mgmt/tree_connect.h | 1 - fs/smb/server/smb2pdu.c | 3 --- 3 files changed, 4 insertions(+), 18 deletions(-) diff --git a/fs/smb/server/mgmt/tree_connect.c b/fs/smb/server/mgmt/tree_connect.c index 94a52a75014a4..9bde1b58f9c46 100644 --- a/fs/smb/server/mgmt/tree_connect.c +++ b/fs/smb/server/mgmt/tree_connect.c @@ -77,7 +77,6 @@ ksmbd_tree_conn_connect(struct ksmbd_work *work, const char *share_name) tree_conn->t_state = TREE_NEW; status.tree_conn = tree_conn; atomic_set(&tree_conn->refcount, 1); - init_waitqueue_head(&tree_conn->refcount_q); ret = xa_err(xa_store(&sess->tree_conns, tree_conn->id, tree_conn, GFP_KERNEL)); @@ -99,14 +98,8 @@ ksmbd_tree_conn_connect(struct ksmbd_work *work, const char *share_name) void ksmbd_tree_connect_put(struct ksmbd_tree_connect *tcon) { - /* - * Checking waitqueue to releasing tree connect on - * tree disconnect. waitqueue_active is safe because it - * uses atomic operation for condition. - */ - if (!atomic_dec_return(&tcon->refcount) && - waitqueue_active(&tcon->refcount_q)) - wake_up(&tcon->refcount_q); + if (atomic_dec_and_test(&tcon->refcount)) + kfree(tcon); } int ksmbd_tree_conn_disconnect(struct ksmbd_session *sess, @@ -118,14 +111,11 @@ int ksmbd_tree_conn_disconnect(struct ksmbd_session *sess, xa_erase(&sess->tree_conns, tree_conn->id); write_unlock(&sess->tree_conns_lock); - if (!atomic_dec_and_test(&tree_conn->refcount)) - wait_event(tree_conn->refcount_q, - atomic_read(&tree_conn->refcount) == 0); - ret = ksmbd_ipc_tree_disconnect_request(sess->id, tree_conn->id); ksmbd_release_tree_conn_id(sess, tree_conn->id); ksmbd_share_config_put(tree_conn->share_conf); - kfree(tree_conn); + if (atomic_dec_and_test(&tree_conn->refcount)) + kfree(tree_conn); return ret; } diff --git a/fs/smb/server/mgmt/tree_connect.h b/fs/smb/server/mgmt/tree_connect.h index a42cdd0510411..f0023d86716f2 100644 --- a/fs/smb/server/mgmt/tree_connect.h +++ b/fs/smb/server/mgmt/tree_connect.h @@ -33,7 +33,6 @@ struct ksmbd_tree_connect { int maximal_access; bool posix_extensions; atomic_t refcount; - wait_queue_head_t refcount_q; unsigned int t_state; }; diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index c50dbbfc4cd62..fe3d3d766719a 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -2181,7 +2181,6 @@ int smb2_tree_disconnect(struct ksmbd_work *work) goto err_out; } - WARN_ON_ONCE(atomic_dec_and_test(&tcon->refcount)); tcon->t_state = TREE_DISCONNECTED; write_unlock(&sess->tree_conns_lock); @@ -2191,8 +2190,6 @@ int smb2_tree_disconnect(struct ksmbd_work *work) goto err_out; } - work->tcon = NULL; - rsp->StructureSize = cpu_to_le16(4); err = ksmbd_iov_pin_rsp(work, rsp, sizeof(struct smb2_tree_disconnect_rsp)); -- 2.51.0