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 AEFCB33CE9A; Fri, 9 Jan 2026 12:06:28 +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=1767960388; cv=none; b=OhHC4KZGfOPuxbKspZ7mBNU74iFiAlEWVKcruILSD8dhbDZTMoULzWuMbeofHYYlDqk66Br6Q5vMtbGPWEYPcgyssQqIGPeRWq0+rh6PeVjE6AqBB+AmIbl1kv9oc8bIChRU2NAM3qaAcqmW+SsAd5hVqo+gDZ4BroFAZTTDGAU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767960388; c=relaxed/simple; bh=//O/ZgPhS9RjBRV7eq57+5/RgC6iq/5jRMRQhfNoRLI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=t3zEb/Xrm2OnBvf8gonWkoyWGn71hC6B5EGQWz2fj6cZ+/6yJM8wMjIYW48JY5GaPmT3gRt4L5DStjRBaB75Dwv4Q6377by2dWC4GmGXVxCsPW0GGxSAGvgtDWEN30mYKkHBFSvgu6wz2rZynypld5KQXNLAii8tBf6yb9tCWW0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=1ZLwJ2Py; 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="1ZLwJ2Py" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 41AF7C19421; Fri, 9 Jan 2026 12:06:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767960388; bh=//O/ZgPhS9RjBRV7eq57+5/RgC6iq/5jRMRQhfNoRLI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1ZLwJ2PylPvfJQdl6V9578Qo2FfRihJE1512WsjQPwBPcN1LFbEJBXM1wsc4VvY1K jDkdRIoPLcF8U5Yx17SDmRrNjHLnPo9iiJoYA5SXd+2343rI8L0m7pBjuxhUbEdLZR sAYQcyili3IQ07IOP8qqSmwZgCK+90SOa++Yte74= 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 6.6 385/737] ipmi: Fix the race between __scan_channels() and deliver_response() Date: Fri, 9 Jan 2026 12:38:44 +0100 Message-ID: <20260109112148.483120545@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260109112133.973195406@linuxfoundation.org> References: <20260109112133.973195406@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 6.6-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 b7d8bf202ed2..4619ee5c744c 100644 --- a/drivers/char/ipmi/ipmi_msghandler.c +++ b/drivers/char/ipmi/ipmi_msghandler.c @@ -3414,8 +3414,6 @@ 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