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Fri, 17 Apr 2026 07:53:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776412414; bh=WYFBone+RdKeGJANQB5WksvtqaVQPIIUpwB7FrTJxLM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Jmd0TAEBDIPG0Wdexll4igX5vJLTTiFEO2Vzr1ZATAQqRdKR7yCGN9dqo3BiyJ7yv 6F8Al4rVG+yKRdXCrVAYTdpRRnrt4ZOmkd6sOf4LRJc5nbBxTaGtAnExo0XW8fX/LI lA93sJzFI4wCUpfbuUqJlxbSrBH6F0TVxM19wu2JvwQUwTAibpvB2mYK0CbcnoqcXO CfPZtOkY9pc/4UorT96so1Y5/txDF9xe+dB9RT9A1d3mrtYGz3s/QtHCyN+TW4/WEu RSRnz9qk7dZ6w7mfxbro0ILPDO9ysqWv3YajgzCd7qyU1iYBKzY2b7/5MD0d00HaxA CYBiz5uqIqD5w== Message-ID: Date: Fri, 17 Apr 2026 09:53:28 +0200 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] powerpc/fadump: reject empty bootargs_append writes To: Pengpeng Hou , Madhavan Srinivasan , Michael Ellerman Cc: Nicholas Piggin , Sourabh Jain , Hari Bathini , Jiri Bohac , Shrikanth Hegde , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260417073907.4985-1-pengpeng@iscas.ac.cn> Content-Language: fr-FR From: "Christophe Leroy (CS GROUP)" In-Reply-To: <20260417073907.4985-1-pengpeng@iscas.ac.cn> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Le 17/04/2026 à 09:39, Pengpeng Hou a écrit : > bootargs_append_store() indexes params[count - 1] when stripping a > trailing newline from the sysfs write buffer. > > kernfs passes zero-length writes through to the store callback, so an > empty write makes that newline check read before the start of params. > > Reject empty writes before looking at the last input byte. > > Fixes: 683eab94da75 ("powerpc/fadump: setup additional parameters for dump capture kernel") > Cc: stable@vger.kernel.org > > Signed-off-by: Pengpeng Hou > --- > arch/powerpc/kernel/fadump.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c > index 4ebc333dd786..03ab5565e420 100644 > --- a/arch/powerpc/kernel/fadump.c > +++ b/arch/powerpc/kernel/fadump.c > @@ -1479,6 +1479,9 @@ static ssize_t bootargs_append_store(struct kobject *kobj, > if (!fw_dump.fadump_enabled || fw_dump.dump_active) > return -EPERM; > > + if (!count) > + return -EINVAL; Why return an error ? A 0 size write is a valid write, it should return 0 I think. > + > if (count >= COMMAND_LINE_SIZE) > return -EINVAL; >