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 5BE401531E1 for ; Tue, 17 Dec 2024 09:31:28 +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=1734427888; cv=none; b=tfeblTtgpUgFocnz26oBv3c/PAwhbKAltmF0D2C1islAeFgCtlO0qFaAv3MuvVql2HOoGrjq9ogWAbI+RlIoPwMvzXT9fkWVSyKp2TUCgOQ1lWPDzzNaaqXxJM3ba7lzXiNQ9Jn7QlMRd3yf3Z1fL1hAzl2xbDnkVOp3dkNTOfw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734427888; c=relaxed/simple; bh=SYTZmenK4QGNJpEy2nBGKdpjr/lfCHT9X4zk7GJOURU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Kyf39CePptbfHqw7QcTVn9JMCZqA70qD9A7IIpZ2dRxx87/6KW+HqmzmhMdwFl4Cr3EeHBYZ4oW8F4Zi1a5qnNC4bPLzUdfhx/XwgI8fuUUi0uuCN/q4m8B3OqBKpYLzrYVoSuhe/93Yo309C20QartXGxlo9xOGwWA5vLjGyEY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fnmFPqAB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fnmFPqAB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 16D0DC4CED3; Tue, 17 Dec 2024 09:31:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1734427887; bh=SYTZmenK4QGNJpEy2nBGKdpjr/lfCHT9X4zk7GJOURU=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=fnmFPqABjl3Hg+asHiCflK1bg/BfRpNMmVXmUrMlj5NmTj/vpPaVfk2UVbqxwl9za fRiqUKTG1aHWLQd0eIk7Mc0WRkzDKpKfLDxsrbxJq9XiAfrL1ta9MHUO7WAzGoOEw3 3/98AYPndgrRKT3AuZ8S2nRyhXytl+mSJTyE8v4cgIte5BcNT+HSMiwqUbCOgufUf+ zbuA71C01qsvmC5pofRdl+j2GCu96gEFNW5IEOuGAktvs5Q6pQkYiyPNvXKxkypZcU c/oO+H+hdj8lnpR4dmsaWQ65k8F/mTa3P7+AWNgDRlYJiLTq4nK7C4PNh4LHVXm7/C T4VwYevdutXuQ== Message-ID: <80e21d04-75a4-4361-8623-0dbadcd4ff2a@kernel.org> Date: Tue, 17 Dec 2024 10:31:23 +0100 Precedence: bulk X-Mailing-List: linux-tegra@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] memory: tegra20-emc: fix an OF node reference bug in tegra_emc_find_node_by_ram_code() To: Joe Hattori , thierry.reding@gmail.com, jonathanh@nvidia.com Cc: linux-tegra@vger.kernel.org References: <20241217091434.1993597-1-joe@pf.is.s.u-tokyo.ac.jp> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 17/12/2024 10:14, Joe Hattori wrote: > As of_find_node_by_name() release the reference of the given OF node, No, it does not. > tegra_emc_find_node_by_ram_code() releases some OF nodes while still in > use, resulting in possible UAFs. Given the DT structure, utilize the > for_each_child_of_node macro and of_get_child_by_name() to avoid the bug. > > This bug was found by an experimental verification tool that I am > developing. > > Fixes: 96e5da7c8424 ("memory: tegra: Introduce Tegra20 EMC driver") > Signed-off-by: Joe Hattori > --- > drivers/memory/tegra/tegra20-emc.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/memory/tegra/tegra20-emc.c b/drivers/memory/tegra/tegra20-emc.c > index 7193f848d17e..9b7d30a21a5b 100644 > --- a/drivers/memory/tegra/tegra20-emc.c > +++ b/drivers/memory/tegra/tegra20-emc.c > @@ -474,14 +474,15 @@ tegra_emc_find_node_by_ram_code(struct tegra_emc *emc) > > ram_code = tegra_read_ram_code(); > > - for (np = of_find_node_by_name(dev->of_node, "emc-tables"); np; > - np = of_find_node_by_name(np, "emc-tables")) { > + for_each_child_of_node(dev->of_node, np) { I don't understand how this change is related to described problem. > + if (!of_node_name_eq(np, "emc-tables")) > + continue; > err = of_property_read_u32(np, "nvidia,ram-code", &value); > if (err || value != ram_code) { > struct device_node *lpddr2_np; > bool cfg_mismatches = false; > > - lpddr2_np = of_find_node_by_name(np, "lpddr2"); > + lpddr2_np = of_get_child_by_name(np, "lpddr2"); Why? > if (lpddr2_np) { > const struct lpddr2_info *info; > > @@ -518,7 +519,6 @@ tegra_emc_find_node_by_ram_code(struct tegra_emc *emc) > } > > if (cfg_mismatches) { > - of_node_put(np); If of_find_node_by_name() drops reference, why this was needed? > continue; Best regards, Krzysztof