[{"id":3687030,"web_url":"http://patchwork.ozlabs.org/comment/3687030/","msgid":"","list_archive_url":null,"date":"2026-05-06T12:27:31","subject":"Re: [PATCH 5/8] i2c: core: fix adapter registration race","submitter":{"id":64666,"url":"http://patchwork.ozlabs.org/api/people/64666/","name":"Johan Hovold","email":"johan@kernel.org"},"content":"On Tue, May 05, 2026 at 04:25:44PM +0200, Johan Hovold wrote:\n> Adapters can be looked up based on their id using i2c_get_adapter()\n> which takes a reference to the embedded struct device.\n> \n> Make sure that the adapter (including its struct device) has been\n> initialised before adding it to the IDR to avoid accessing uninitialised\n> data which could, for example, lead to NULL-pointer dereferences or\n> use-after-free.\n> \n> Fixes: 6e13e6418418 (\"i2c: Add i2c_add_numbered_adapter()\")\n> Cc: stable@vger.kernel.org\t# 2.6.22\n> Signed-off-by: Johan Hovold \n> ---\n> drivers/i2c/i2c-core-base.c | 8 ++++++--\n> 1 file changed, 6 insertions(+), 2 deletions(-)\n> \n> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c\n> index 31f7d43e4ab5..be909d6bc776 100644\n> --- a/drivers/i2c/i2c-core-base.c\n> +++ b/drivers/i2c/i2c-core-base.c\n> @@ -1587,6 +1587,10 @@ static int i2c_register_adapter(struct i2c_adapter *adap)\n> \tif (res)\n> \t\tgoto out_reg;\n> \n> +\tmutex_lock(&core_lock);\n> +\tidr_replace(&i2c_adapter_idr, adap, adap->nr);\n> +\tmutex_unlock(&core_lock);\n\nSashiko points out that this needs to go before registering the adapter\n(for now) as i2c-dev registers the chardev from a bus notifier callback.\n\n> +\n> \tdev_dbg(&adap->dev, \"adapter [%s] registered\\n\", adap->name);\n> \n> \t/* create pre-declared device nodes */\n\nJohan","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-i2c@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=r1FTydVA;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c04:e001:36c::12fc:5321; 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