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 E89103A0E9A; Thu, 15 Jan 2026 17:25:35 +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=1768497936; cv=none; b=pIwqKVJqbcjSjayXSaX/jOyVHySdV+3aZEHIXG0eVP5ZUfbvFs7Fgf00QG4peh0FPmqCDvyKPX4yRNDtFxqA22EihQCxsg6ADBKKg1w/gEZ026EZcsJcMawnwyRrgknL5Lf2/BaXiSfFYFY9DfJn6Xh8itzsZQalEzzTBS/l+Dk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768497936; c=relaxed/simple; bh=2wMi27ImmayVSaTbtrpotrjBBUswQJD3bv4ehfLHZ+4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OfPyuThlYelwTqNehrHf5hAAuvb804FgO/Fdtb3/KTpskVl59REIdQP67xVw1b5eXX+KJAeVIKXHDvAa/HmO+GXOZZGeoT0JcWWWM+4YgAiTguc6Rw5icX3AZUBVZyo7ayQax/wC2dq2FnwxW8Kh1h1N4l6QWtSF0QqM7w26SQ0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=l+YQ9bQ+; 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="l+YQ9bQ+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73DC8C116D0; Thu, 15 Jan 2026 17:25:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1768497935; bh=2wMi27ImmayVSaTbtrpotrjBBUswQJD3bv4ehfLHZ+4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=l+YQ9bQ+XlBDvE1d6i4kinFyxFkxeqDspOIuLuvyV69pThp5c6CsQ+zNi/zP3iCyp Y16ufuO6phKxveweQTfnXPzu3vOYR7EkhwqGaDjMqTzLBkKJScd4Y7Wteuw7zGoJp6 81ZUEisE4R9PZ51PK0BTPpLifJqGi9ca7iLUE824= 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 5.15 256/554] ipmi: Fix the race between __scan_channels() and deliver_response() Date: Thu, 15 Jan 2026 17:45:22 +0100 Message-ID: <20260115164255.501457202@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260115164246.225995385@linuxfoundation.org> References: <20260115164246.225995385@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 5.15-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 af563ee827aa..98ccba19292a 100644 --- a/drivers/char/ipmi/ipmi_msghandler.c +++ b/drivers/char/ipmi/ipmi_msghandler.c @@ -3292,8 +3292,6 @@ 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