From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 E090135BDAA; Thu, 30 Jul 2026 15:51:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785426720; cv=none; b=ehGOG0SHu1jHXB/iaC6KseF9HsyWAGYVynzvvd0N0tFPRk6S39rI68Tf/ZflVV/YlZFSNo+Expt+K/2W09HG1HJcZGyy96evb1pEAjthcWYQhLyi+HB6OaeOTsL+yMCxGyYcu/2tbq5jG4tSzP/e819kRVpNQAuIukCOfiu1Mkk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785426720; c=relaxed/simple; bh=kWuqpO4Xlxa0iCF4jFbUBuZ2ODEDOUQIUDp49IEyDuU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MQAS5nu7z3TGzPfd3iqrRKA6oLkrksWGvrzVkHvg8e8R1MpRTwPnFx1+vWSAKfNlAOeeIFBSZ0dox2JmDTeW3h83MpUgBtGY778B1EGrsC3A9pxVyIVCyH2yGSpIVpZY7lg2DhUMgLBGoqH4IWcbKb5J+LJHKDFFWj7S/70oUcA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=iJblPllo; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="iJblPllo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 462381F000E9; Thu, 30 Jul 2026 15:51:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785426718; bh=+QgWX+OnrWgXO3TZ6gaM/w9UEiMCnb0ehI6KNYMHmz4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=iJblPlloS8MRMXhuq65Jt0SFsBYUjSs9HIROOaQM7gOJBl+F6N0lqke2gzhpeZejO xxQ06Lw7g09vKtA2LCr9OZPCpI0fgEDxQO5dhEw2WsjdOf3NRH5JR4FMji6jEXEeGO Z3sP6Mk04IJmscnjZKKbEmXL2LTXZgMNl18Im+C4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mingyu Wang <25181214217@stu.xidian.edu.cn>, Andi Shyti , Sasha Levin Subject: [PATCH 6.12 474/602] i2c: i801: fix hardware state machine corruption in error path Date: Thu, 30 Jul 2026 16:14:26 +0200 Message-ID: <20260730141445.924352946@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141435.976815864@linuxfoundation.org> References: <20260730141435.976815864@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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mingyu Wang <25181214217@stu.xidian.edu.cn> [ Upstream commit 10dd1a736d557e310a77117832874729a0175d57 ] A severe livelock and subsequent Hung Task panic were observed in the i2c-i801 driver during concurrent Fuzzing. The crash is caused by an unconditional hardware register cleanup in the error handling path of i801_access(). When i801_check_pre() fails (e.g., returning -EBUSY because the SMBus controller is actively used by BIOS/ACPI), the kernel does not actually acquire the hardware ownership. However, the code jumps to the 'out' label and executes: iowrite8(SMBHSTSTS_INUSE_STS | STATUS_FLAGS, SMBHSTSTS(priv)); This forcefully clears the INUSE_STS lock and resets the hardware status flags without owning the controller. Doing so interrupts ongoing BIOS/ACPI transactions and totally corrupts the SMBus hardware state machine. Consequently, all subsequent i801_access() calls fail at the pre-check stage, triggering an endless stream of "SMBus is busy, can't use it!" error logs. Over a slow serial console, this printk flood monopolizes the CPU (Console Livelock), starving other processes trying to acquire the mmap_lock down_read semaphore, ultimately triggering the hung task watchdog. Fix this by moving the 'out' label below the hardware register cleanup. If i801_check_pre() fails, we safely bypass the iowrite8() and only release the software locks (pm_runtime and mutex), strictly adhering to the rule of not releasing resources that were never acquired. Fixes: 1f760b87e54c ("i2c: i801: Call i801_check_pre() from i801_access()") Signed-off-by: Mingyu Wang <25181214217@stu.xidian.edu.cn> Cc: # v6.3+ Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20260512093534.348655-1-w15303746062@163.com Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/i2c/busses/i2c-i801.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/i2c/busses/i2c-i801.c +++ b/drivers/i2c/busses/i2c-i801.c @@ -930,13 +930,13 @@ static s32 i801_access(struct i2c_adapte */ if (hwpec) outb_p(inb_p(SMBAUXCTL(priv)) & ~SMBAUXCTL_CRC, SMBAUXCTL(priv)); -out: /* * Unlock the SMBus device for use by BIOS/ACPI, * and clear status flags if not done already. */ outb_p(SMBHSTSTS_INUSE_STS | STATUS_FLAGS, SMBHSTSTS(priv)); +out: pm_runtime_mark_last_busy(&priv->pci_dev->dev); pm_runtime_put_autosuspend(&priv->pci_dev->dev); mutex_unlock(&priv->acpi_lock);