From patchwork Mon Apr 24 19:18:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fedor Pchelkin X-Patchwork-Id: 13222509 X-Patchwork-Delegate: toke@redhat.com Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68F34C77B61 for ; Mon, 24 Apr 2023 19:19:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231398AbjDXTTZ (ORCPT ); Mon, 24 Apr 2023 15:19:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35826 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231303AbjDXTTY (ORCPT ); Mon, 24 Apr 2023 15:19:24 -0400 Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0FD454C2B; Mon, 24 Apr 2023 12:19:23 -0700 (PDT) Received: from fpc.. (unknown [46.242.14.200]) by mail.ispras.ru (Postfix) with ESMTPSA id 2847A4076277; Mon, 24 Apr 2023 19:19:21 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.ispras.ru 2847A4076277 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ispras.ru; s=default; t=1682363961; bh=Ndv3UKrB3QzOIT2rE3GkXyq8UTij4TcY2JmMRnQH7YU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mpvrbInnWHLEaNECUq4UUY726unmqUX7LoG9JOs4bRBcbyfF38K71RnSZfVeNI0bn Y64XsH3P09pSVn25rmYiUoRvwAkOlmPvn3osGmpBgyqKU8oFHROuFMGbkBVJvERuG8 x47QuJ0UHqRfAVfTvEM5Y7Q+pyq1FHutBYkEQ4O8= From: Fedor Pchelkin To: =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , Kalle Valo Cc: Fedor Pchelkin , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Senthil Balasubramanian , "John W. Linville" , Vasanthakumar Thiagarajan , Sujith , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Alexey Khoroshilov , lvc-project@linuxtesting.org, syzbot+f2cb6e0ffdb961921e4d@syzkaller.appspotmail.com, syzbot+df61b36319e045c00a08@syzkaller.appspotmail.com Subject: [PATCH v2] wifi: ath9k: fix races between ath9k_wmi_cmd and ath9k_wmi_ctrl_rx Date: Mon, 24 Apr 2023 22:18:26 +0300 Message-Id: <20230424191826.117354-1-pchelkin@ispras.ru> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230424191158.iebfqubeanurdabk@fpc> References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org Currently, the synchronization between ath9k_wmi_cmd() and ath9k_wmi_ctrl_rx() is exposed to a race condition which, although being rather unlikely, can lead to invalid behaviour of ath9k_wmi_cmd(). Consider the following scenario: CPU0 CPU1 ath9k_wmi_cmd(...) mutex_lock(&wmi->op_mutex) ath9k_wmi_cmd_issue(...) wait_for_completion_timeout(...) --- timeout --- /* the callback is being processed * before last_seq_id became zero */ ath9k_wmi_ctrl_rx(...) spin_lock_irqsave(...) /* wmi->last_seq_id check here * doesn't detect timeout yet */ spin_unlock_irqrestore(...) /* last_seq_id is zeroed to * indicate there was a timeout */ wmi->last_seq_id = 0 mutex_unlock(&wmi->op_mutex) return -ETIMEDOUT ath9k_wmi_cmd(...) mutex_lock(&wmi->op_mutex) /* the buffer is replaced with * another one */ wmi->cmd_rsp_buf = rsp_buf wmi->cmd_rsp_len = rsp_len ath9k_wmi_cmd_issue(...) spin_lock_irqsave(...) spin_unlock_irqrestore(...) wait_for_completion_timeout(...) /* the continuation of the * callback left after the first * ath9k_wmi_cmd call */ ath9k_wmi_rsp_callback(...) /* copying data designated * to already timeouted * WMI command into an * inappropriate wmi_cmd_buf */ memcpy(...) complete(&wmi->cmd_wait) /* awakened by the bogus callback * => invalid return result */ mutex_unlock(&wmi->op_mutex) return 0 To fix this, move ath9k_wmi_rsp_callback() under wmi_lock inside ath9k_wmi_ctrl_rx() so that the wmi->cmd_wait can be completed only for initially designated wmi_cmd call, otherwise the path would be rejected with last_seq_id check. Also move recording the rsp buffer and length into ath9k_wmi_cmd_issue() under the same wmi_lock with last_seq_id update to avoid their racy changes. Found by Linux Verification Center (linuxtesting.org) with Syzkaller. Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.") Reported-and-tested-by: syzbot+df61b36319e045c00a08@syzkaller.appspotmail.com Signed-off-by: Fedor Pchelkin --- v2: do not extract ath9k_wmi_rsp_callback() internals, rephrase description drivers/net/wireless/ath/ath9k/wmi.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/net/wireless/ath/ath9k/wmi.c b/drivers/net/wireless/ath/ath9k/wmi.c index d652c647d56b..688453a2e53a 100644 --- a/drivers/net/wireless/ath/ath9k/wmi.c +++ b/drivers/net/wireless/ath/ath9k/wmi.c @@ -242,10 +242,10 @@ static void ath9k_wmi_ctrl_rx(void *priv, struct sk_buff *skb, spin_unlock_irqrestore(&wmi->wmi_lock, flags); goto free_skb; } - spin_unlock_irqrestore(&wmi->wmi_lock, flags); /* WMI command response */ ath9k_wmi_rsp_callback(wmi, skb); + spin_unlock_irqrestore(&wmi->wmi_lock, flags); free_skb: kfree_skb(skb); @@ -283,7 +283,8 @@ int ath9k_wmi_connect(struct htc_target *htc, struct wmi *wmi, static int ath9k_wmi_cmd_issue(struct wmi *wmi, struct sk_buff *skb, - enum wmi_cmd_id cmd, u16 len) + enum wmi_cmd_id cmd, u16 len, + u8 *rsp_buf, u32 rsp_len) { struct wmi_cmd_hdr *hdr; unsigned long flags; @@ -293,6 +294,11 @@ static int ath9k_wmi_cmd_issue(struct wmi *wmi, hdr->seq_no = cpu_to_be16(++wmi->tx_seq_id); spin_lock_irqsave(&wmi->wmi_lock, flags); + + /* record the rsp buffer and length */ + wmi->cmd_rsp_buf = rsp_buf; + wmi->cmd_rsp_len = rsp_len; + wmi->last_seq_id = wmi->tx_seq_id; spin_unlock_irqrestore(&wmi->wmi_lock, flags); @@ -333,11 +339,7 @@ int ath9k_wmi_cmd(struct wmi *wmi, enum wmi_cmd_id cmd_id, goto out; } - /* record the rsp buffer and length */ - wmi->cmd_rsp_buf = rsp_buf; - wmi->cmd_rsp_len = rsp_len; - - ret = ath9k_wmi_cmd_issue(wmi, skb, cmd_id, cmd_len); + ret = ath9k_wmi_cmd_issue(wmi, skb, cmd_id, cmd_len, rsp_buf, rsp_len); if (ret) goto out;