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 F2DDD2222CB; Mon, 29 Dec 2025 16:22:09 +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=1767025330; cv=none; b=ETz6uoVZXNxsJIm8PCS8jAmObWwDOC2ohRQrip6kzGTJJB2ej3RRSA9ijUOqBb7GMdtHPlcLeceAYVL4UFq64XXteO6bOWKwacX2RTtxMK5ULKSAEqfwOK8/xGctNwnxQyc6fnTLlK0+vvb0fxXL2rKL/wCM5AOGcLbwrS9/y98= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767025330; c=relaxed/simple; bh=tgGSg42yH0BdPKMlpVuD3OMyNimZPvZttiW6lmVWJZg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PRlTZG7lRLPVChkLFfu9M3sNuLCZIlmFlIWT/mQGqi2Sa9k3hTbCaGNhDDz31hjPVo/FXgQJUE2Rgbek7ZwHzILJufjmYl4f+LryrZkzTE7jqwMkYtQ9SaW1ngP//GuI0/qjMaLU/GDePU3wMwb8ZkfOzAeEV7hNNI4p2J7rLDc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=hBOmYdjJ; 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="hBOmYdjJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7AB76C4CEF7; Mon, 29 Dec 2025 16:22:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767025329; bh=tgGSg42yH0BdPKMlpVuD3OMyNimZPvZttiW6lmVWJZg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hBOmYdjJVWJwVwOmpV2b8kkm/ZOkgcD61D79TH4Ek+6rckaK0rVVDK9e9SOqlIBj0 wCfHX7Emy77jB96IbUHYdhlXbuxTmqZmv5DEhOvzErlEpisuHHcygx8XjdS21riM1a dwdAvH7k6XRDX1htLpYBb7SeYUn53HH90kIxnOAw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jinhui Guo , Corey Minyard , Sasha Levin Subject: [PATCH 6.18 176/430] ipmi: Fix the race between __scan_channels() and deliver_response() Date: Mon, 29 Dec 2025 17:09:38 +0100 Message-ID: <20251229160730.837385555@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251229160724.139406961@linuxfoundation.org> References: <20251229160724.139406961@linuxfoundation.org> User-Agent: quilt/0.69 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-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jinhui Guo [ Upstream commit 936750fdba4c45e13bbd17f261bb140dd55f5e93 ] The race window between __scan_channels() and deliver_response() causes the parameters of some channels to be set to 0. 1.[CPUA] __scan_channels() issues an IPMI request and waits with wait_event() until all channels have been scanned. wait_event() internally calls might_sleep(), which might yield the CPU. (Moreover, an interrupt can preempt wait_event() and force the task to yield the CPU.) 2.[CPUB] deliver_response() is invoked when the CPU receives the IPMI response. After processing a IPMI response, deliver_response() directly assigns intf->wchannels to intf->channel_list and sets intf->channels_ready to true. However, not all channels are actually ready for use. 3.[CPUA] Since intf->channels_ready is already true, wait_event() never enters __wait_event(). __scan_channels() immediately clears intf->null_user_handler and exits. 4.[CPUB] Once intf->null_user_handler is set to NULL, deliver_response() ignores further IPMI responses, leaving the remaining channels zero-initialized and unusable. CPUA CPUB ------------------------------- ----------------------------- __scan_channels() intf->null_user_handler = channel_handler; send_channel_info_cmd(intf, 0); wait_event(intf->waitq, intf->channels_ready); do { might_sleep(); deliver_response() channel_handler() intf->channel_list = intf->wchannels + set; intf->channels_ready = true; send_channel_info_cmd(intf, intf->curr_channel); if (condition) break; __wait_event(wq_head, condition); } while(0) intf->null_user_handler = NULL; deliver_response() if (!msg->user) if (intf->null_user_handler) rv = -EINVAL; return rv; ------------------------------- ----------------------------- Fix the race between __scan_channels() and deliver_response() by deferring both the assignment intf->channel_list = intf->wchannels and the flag intf->channels_ready = true until all channels have been successfully scanned or until the IPMI request has failed. Signed-off-by: Jinhui Guo Message-ID: <20250930074239.2353-2-guojinhui.liam@bytedance.com> Signed-off-by: Corey Minyard Signed-off-by: Sasha Levin --- drivers/char/ipmi/ipmi_msghandler.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c index 3700ab4eba3e..d3f84deee451 100644 --- a/drivers/char/ipmi/ipmi_msghandler.c +++ b/drivers/char/ipmi/ipmi_msghandler.c @@ -3417,8 +3417,6 @@ channel_handler(struct ipmi_smi *intf, struct ipmi_recv_msg *msg) intf->channels_ready = true; wake_up(&intf->waitq); } else { - intf->channel_list = intf->wchannels + set; - intf->channels_ready = true; rv = send_channel_info_cmd(intf, intf->curr_channel); } -- 2.51.0