From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from cse.ust.hk (cssvr7.cse.ust.hk [143.89.41.157]) (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 99793239E9A for ; Tue, 14 Oct 2025 01:55:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=143.89.41.157 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760406961; cv=pass; b=Z+hVzyWP7CT3RpMbqKyek5ZncitUNIybgr9v9FyydeYDhXDjoeZjW8l3xXDEDzetbUEqh+y6vBrC3TCAfrYQSuc9idDvw8jxwk9vmFSOTd/Hk4U8zs1sKxVHLewilfVed3FXDH45TNxaLSI4zMMYwcEMVXCYxDPBf9K/EFDbxqs= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760406961; c=relaxed/simple; bh=aY1wVyIBu+P/Agy6EzxeV0N9FDZmNyKBt3V+RY8feUw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=PYO1WUGpN1bdLCvXI767v+aF6GACun12uag+dwaRFuIocdSOERN2k+ZENbib/8SVNT/+HNoeSK8si10rTHze1PcDVSEIOq/64cV27toRvqLIHMi/68GAV0FvDh9cnm7cG+qSI1U8TPC1RWKy6sD1neYT05zhw5HXGzfP1sPU7ao= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=cse.ust.hk; spf=pass smtp.mailfrom=cse.ust.hk; dkim=pass (1024-bit key) header.d=cse.ust.hk header.i=@cse.ust.hk header.b=lDaXZY7X; arc=pass smtp.client-ip=143.89.41.157 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=cse.ust.hk Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=cse.ust.hk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=cse.ust.hk header.i=@cse.ust.hk header.b="lDaXZY7X" Received: from osx.local (ecs-119-8-240-30.compute.hwclouds-dns.com [119.8.240.30]) (authenticated bits=0) by cse.ust.hk (8.18.1/8.12.5) with ESMTPSA id 59E1tWbH3266543 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Tue, 14 Oct 2025 09:55:39 +0800 ARC-Seal: i=1; a=rsa-sha256; d=cse.ust.hk; s=arccse; t=1760406940; cv=none; b=TG2eDPngy1F+FYyMTrlX6x9XY1uQqFwbkPSCOlvTF/Ifjud9UMkFGMME2umX0DLmHDYOT/pJlKrribTS8cuftD+BNHJyxtKdbRMolyE3Brer19UOlur91nn+IBmP9bQuAylgnsiHcJn61XN0E0EHXXffD8rlBrSFZTWm3I0PDPg= ARC-Message-Signature: i=1; a=rsa-sha256; d=cse.ust.hk; s=arccse; t=1760406940; c=relaxed/relaxed; bh=G++JBLc5OONg4P4tABuFONmwLMMGyA7zCS68NMAH4tE=; h=DKIM-Signature:Date:From:To:Subject:Message-ID:MIME-Version; b=xuDtpo1OE0ISqB+jWu8ylzK7bTAOXc+Rxp/6SiKCQ2aogR6L5Wh1ET4QZY56N6vHjiQj3jW88HfGulGLtvdw5hESfFugKEEmmS08BFVo8eSF/6+zxVBYIIsKgfB4I3+5LmnFTO/7AEtffJYH4J62BVDw9a0Sha2DkTj7wEHCy2I= ARC-Authentication-Results: i=1; cse.ust.hk DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cse.ust.hk; s=cseusthk; t=1760406940; bh=G++JBLc5OONg4P4tABuFONmwLMMGyA7zCS68NMAH4tE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=lDaXZY7XrO+vLBk8Z77JHj8UzAyV9y4RKBSEJecsFCCaacVjyj6Zg6G1i8Mj6d2tt zZKdkfrVWxXyWE7IAW5il+8AE8HqzDKdyRvvqAW0EAqapN1J1Td0vAyQ11tzBz9WlA uVKCKR51ouC8TPV7jzC6W4IyoBUBnp+4hDENL7FI= Date: Tue, 14 Oct 2025 09:55:26 +0800 From: Shuhao Fu To: Frank Li Cc: Alexandre Belloni , linux-i3c@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] i3c: fix refcount inconsistency in i3c_master_register Message-ID: References: <20251013210953.GA2124@DESKTOP-2SPVBES.localdomain> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Env-From: sfual On Mon, Oct 13, 2025 at 06:01:19PM -0400, Frank Li wrote: > On Tue, Oct 14, 2025 at 05:09:53AM +0800, Shuhao Fu wrote: > > On Mon, Oct 13, 2025 at 04:19:00PM -0400, Frank Li wrote: > > > On Fri, Oct 10, 2025 at 02:34:08PM +0800, Shuhao Fu wrote: > > > > On Thu, Oct 09, 2025 at 12:17:11PM -0400, Frank Li wrote: > > > > > On Wed, Oct 08, 2025 at 03:27:09PM +0800, Shuhao Fu wrote: > > > > > > In `i3c_master_register`, a possible refcount inconsistency has been > > > > > > identified, causing possible resource leak. > > > > > > > > > > > > Function `of_node_get` increases the refcount of `parent->of_node`. If > > > > > > function `i3c_bus_init` fails, the function returns immediately without > > > > > > a corresponding decrease, resulting in an inconsistent refcounter. > > > > > > > > > > > > In this patch, an extra goto label is added to ensure the balance of > > > > > > refcount when `i3c_bus_init` fails. > > > > > > > > > > > > Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure") > > > > > > Signed-off-by: Shuhao Fu > > > > > > --- > > > > > > drivers/i3c/master.c | 5 ++++- > > > > > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > > > > > > > > > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c > > > > > > index d946db75d..9f4fe98d2 100644 > > > > > > --- a/drivers/i3c/master.c > > > > > > +++ b/drivers/i3c/master.c > > > > > > @@ -2885,7 +2885,7 @@ int i3c_master_register(struct i3c_master_controller *master, > > > > > > > > > > > > ret = i3c_bus_init(i3cbus, master->dev.of_node); > > > > > > if (ret) > > > > > > - return ret; > > > > > > + goto err_put_of_node; > > > > > > > > > > I think it'd better to set release function for master dev to release > > > > > of_node because of_node_put() also missed at i3c_master_unregister() > > > > > > > > > > you can refer drivers/base/platform.c > > > > > > > > > > Frank > > > > > > > > Do you mean that we should do `of_node_release` in > > > > `platform_device_release`, instead of respecting the refcounting via > > > > `of_node_put`? > > > > > > Sorry, I checked code again. > > > > > > static void i3c_masterdev_release(struct device *dev) > > > { > > > ... > > > of_node_put(dev->of_node); > > > } > > > > > > i3c_master_register() > > > { > > > ... > > > master->dev.release = i3c_masterdev_release; > > > ... > > > }; > > > > > > Suppose of_node_put() will be auto called when put_device(&master->dev); > > > > > > Do you really meet the problem or just static anaysis? > > > > > > Frank > > > > Honestly, it's from static analysis. > > > > My apologies for overlooking the release handle. I checked the code once > > again. It still looks suspicious as it would not call `put_device` if it > > fails. I also checked call sites related to `i3c_master_register` and > > they dont seem to do the clean-up if register fails. > > > @@ -2814,10 +2816,6 @@ int i3c_master_register(struct i3c_master_controller *master, > INIT_LIST_HEAD(&master->boardinfo.i2c); > INIT_LIST_HEAD(&master->boardinfo.i3c); > > - ret = i3c_bus_init(i3cbus, master->dev.of_node); > - if (ret) > - return ret; > - > device_initialize(&master->dev); > dev_set_name(&master->dev, "i3c-%d", i3cbus->id); > > @@ -2825,6 +2823,10 @@ int i3c_master_register(struct i3c_master_controller *master, > master->dev.coherent_dma_mask = parent->coherent_dma_mask; > master->dev.dma_parms = parent->dma_parms; > > + ret = i3c_bus_init(i3cbus, master->dev.of_node); > + if (ret) > + goto err_put_dev; > + > > I inject at error at i3c_bus_init(), above code can trigger i3c_masterdev_release, > which call of_node_put(). > > Frank > Thank you for fixing the refcounting issue. May I kindly ask for a reported-by tag for this fix "Reported-by: Shuhao Fu "? Thanks, Shuhao > > > > Shuhao > > > > > > > > > > > > > > > > > > > > > device_initialize(&master->dev); > > > > > > dev_set_name(&master->dev, "i3c-%d", i3cbus->id); > > > > > > @@ -2973,6 +2973,9 @@ int i3c_master_register(struct i3c_master_controller *master, > > > > > > err_put_dev: > > > > > > put_device(&master->dev); > > > > > > > > > > > > +err_put_of_node: > > > > > > + of_node_put(master->dev.of_node); > > > > > > + > > > > > > return ret; > > > > > > } > > > > > > EXPORT_SYMBOL_GPL(i3c_master_register); > > > > > > -- > > > > > > 2.39.5 (Apple Git-154) > > > > > > > > > > > > > > > > > > -- > > > > > > linux-i3c mailing list > > > > > > linux-i3c@lists.infradead.org > > > > > > https://apc01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.infradead.org%2Fmailman%2Flistinfo%2Flinux-i3c&data=05%7C02%7Csfual%40connect.ust.hk%7Cdbe4f1ecc0c84f304fca08de0aa414ff%7C6c1d415239d044ca88d9b8d6ddca0708%7C1%7C0%7C638959897018898845%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=%2BmCDBh4d6Se%2BuO5xJgSDVupMRir7ZFH7f8RtzGUucoE%3D&reserved=0 > > > > > > > > -- > > > > linux-i3c mailing list > > > > linux-i3c@lists.infradead.org > > > > https://apc01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.infradead.org%2Fmailman%2Flistinfo%2Flinux-i3c&data=05%7C02%7Csfual%40connect.ust.hk%7Cdbe4f1ecc0c84f304fca08de0aa414ff%7C6c1d415239d044ca88d9b8d6ddca0708%7C1%7C0%7C638959897018922222%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=MdqJwKEKImd8UAQ0hyHjWyZx8vX1YSxU%2FqKDgpF0JPA%3D&reserved=0