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 82AB41B424F; Sun, 7 Sep 2025 20:21:43 +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=1757276503; cv=none; b=rjlPdYB3hPX3GcD9zumX699db6zPNz2H0VYTDQrQl5WqJ1ABf11KS5gV/in/c3zgIClIaSxVzz4P3w7dKNY3U8etLvm8jgfXj3o31Gm4lBMBnw0Pcmjl/EdIcsZdRsXueUyX5T92bxk4aQizTT4t5H4Wm4oD/w/s2fzG+pT1L5A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757276503; c=relaxed/simple; bh=Y40r+SWOfe32VC5fudmzH6lmvNkcat6iHvMECARg3FE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=R0w+o52+ZRkz6aPK2u0QDFucNoFRlbCS/fS3j7YKhC7xTfhydFRQuxof2cPSBVCvJjmujdhsQlTEdxcKnFD8WyVOG8SD/Mx0bakXL6vgDYlcQZfgUCdPhQ1kRdIvEB6l17Gn1XcLwvNDwv7piwYro9oWC397DDqBJJz+UwMs2hA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=JsSEHtND; 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="JsSEHtND" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 09D4CC4CEF0; Sun, 7 Sep 2025 20:21:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1757276503; bh=Y40r+SWOfe32VC5fudmzH6lmvNkcat6iHvMECARg3FE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JsSEHtND6cTo4gftyAeJ9k/wv61vzXZUEKlBpa+7t+yyJUzLhH4YPnwnPUd2HVOiO HEvElheuh/Zc4C2RYxUlrMrBGP/inl+pSQQB6K4xE3oKtpnDLXtDb8tfGbYsDhASxO HkJ+6vlaUCzKPWjZ4hRcsayBVHRWILubQlLkCLdw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Arend van Spriel , Duoming Zhou , Johannes Berg , Sasha Levin Subject: [PATCH 6.6 020/121] wifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work Date: Sun, 7 Sep 2025 21:57:36 +0200 Message-ID: <20250907195610.334436176@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250907195609.817339617@linuxfoundation.org> References: <20250907195609.817339617@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Duoming Zhou [ Upstream commit 9cb83d4be0b9b697eae93d321e0da999f9cdfcfc ] The brcmf_btcoex_detach() only shuts down the btcoex timer, if the flag timer_on is false. However, the brcmf_btcoex_timerfunc(), which runs as timer handler, sets timer_on to false. This creates critical race conditions: 1.If brcmf_btcoex_detach() is called while brcmf_btcoex_timerfunc() is executing, it may observe timer_on as false and skip the call to timer_shutdown_sync(). 2.The brcmf_btcoex_timerfunc() may then reschedule the brcmf_btcoex_info worker after the cancel_work_sync() has been executed, resulting in use-after-free bugs. The use-after-free bugs occur in two distinct scenarios, depending on the timing of when the brcmf_btcoex_info struct is freed relative to the execution of its worker thread. Scenario 1: Freed before the worker is scheduled The brcmf_btcoex_info is deallocated before the worker is scheduled. A race condition can occur when schedule_work(&bt_local->work) is called after the target memory has been freed. The sequence of events is detailed below: CPU0 | CPU1 brcmf_btcoex_detach | brcmf_btcoex_timerfunc | bt_local->timer_on = false; if (cfg->btcoex->timer_on) | ... | cancel_work_sync(); | ... | kfree(cfg->btcoex); // FREE | | schedule_work(&bt_local->work); // USE Scenario 2: Freed after the worker is scheduled The brcmf_btcoex_info is freed after the worker has been scheduled but before or during its execution. In this case, statements within the brcmf_btcoex_handler() — such as the container_of macro and subsequent dereferences of the brcmf_btcoex_info object will cause a use-after-free access. The following timeline illustrates this scenario: CPU0 | CPU1 brcmf_btcoex_detach | brcmf_btcoex_timerfunc | bt_local->timer_on = false; if (cfg->btcoex->timer_on) | ... | cancel_work_sync(); | ... | schedule_work(); // Reschedule | kfree(cfg->btcoex); // FREE | brcmf_btcoex_handler() // Worker /* | btci = container_of(....); // USE The kfree() above could | ... also occur at any point | btci-> // USE during the worker's execution| */ | To resolve the race conditions, drop the conditional check and call timer_shutdown_sync() directly. It can deactivate the timer reliably, regardless of its current state. Once stopped, the timer_on state is then set to false. Fixes: 61730d4dfffc ("brcmfmac: support critical protocol API for DHCP") Acked-by: Arend van Spriel Signed-off-by: Duoming Zhou Link: https://patch.msgid.link/20250822050839.4413-1-duoming@zju.edu.cn Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin --- drivers/net/wireless/broadcom/brcm80211/brcmfmac/btcoex.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/btcoex.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/btcoex.c index 00794086cc7c9..bf80675667ba3 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/btcoex.c +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/btcoex.c @@ -392,10 +392,8 @@ void brcmf_btcoex_detach(struct brcmf_cfg80211_info *cfg) if (!cfg->btcoex) return; - if (cfg->btcoex->timer_on) { - cfg->btcoex->timer_on = false; - timer_shutdown_sync(&cfg->btcoex->timer); - } + timer_shutdown_sync(&cfg->btcoex->timer); + cfg->btcoex->timer_on = false; cancel_work_sync(&cfg->btcoex->work); -- 2.50.1