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Fri, 17 Apr 2026 09:30:37 +0000 (GMT) Message-ID: Date: Fri, 17 Apr 2026 15:00:36 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 , "Christophe Leroy (CS GROUP)" , 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: en-US From: Sourabh Jain In-Reply-To: <20260417073907.4985-1-pengpeng@iscas.ac.cn> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: ZpuidKosRXgK6xFjk55b3s7C5Ioqw6nb X-Proofpoint-ORIG-GUID: FgBNQs713CIGiH4qqfKSSI_ZCZl0tnqc X-Authority-Analysis: v=2.4 cv=WbE8rUhX c=1 sm=1 tr=0 ts=69e1fdc4 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VwQbUJbxAAAA:8 a=ISPHxN_rHVCBf9gf85UA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDE3MDA5MiBTYWx0ZWRfXzZJRh73LJd6m sOfnU4KimGoboDbpWbqRA/IniEZ+4+85ZNQUGiMgaOJ2+979mCXqtEPV9t9p5/4ZuQWN+ncoyk0 8WV5n6fNTy7hNu9Rev7m+W7v3E2WsOlQ0CusdTZ1vQKI/UDk1D0nIpBhZSypUl8ZSaao8jH0G2r WQPplU4UO9xefl2qZUTQLC8Q/VkAWIUNFThYG8R7VHwxA2EpU3tQCIYSn2pO9h48InZss56XDCD n8gCqgT2awh8rZo5tKOwkYMppXtNqf6haXR37Z6VVC4nlyivCHtWSngvWgh+hb4UL7S7xFY0Lt4 u6KlBY6jllNGw9q0VgFAXuM3rpt0B3S53PUVCge22WWlKC2kfxpp76ubqGk1tPZLON1cwh5aNl3 XVPZ+rsJ4nNlB2/ihlWZf/XeYReFVmxGEvfI1ke7AJnZLuyuRgIHFEjtMijB9eRTzcFnBZD1HdA qrJ842Y3bjravnwF1Hg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-16_04,2026-04-16_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 bulkscore=0 priorityscore=1501 spamscore=0 clxscore=1011 phishscore=0 impostorscore=0 adultscore=0 malwarescore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604070000 definitions=main-2604170092 On 17/04/26 13:09, Pengpeng Hou wrote: > 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; How you manage to call this function with count as 0? > + > if (count >= COMMAND_LINE_SIZE) > return -EINVAL; >