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Wed, 22 Apr 2026 04:49:32 +0000 (GMT) Received: from [9.123.14.230] (unknown [9.123.14.230]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTPS; Wed, 22 Apr 2026 04:49:32 +0000 (GMT) Message-ID: Date: Wed, 22 Apr 2026 10:19:31 +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/pseries/lparcfg: size the scratch buffer to the system parameter payload To: Pengpeng Hou , maddy@linux.ibm.com Cc: mpe@ellerman.id.au, npiggin@gmail.com, chleroy@kernel.org, kees@kernel.org, srikar@linux.ibm.com, nathanl@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20260401160316.88551-1-pengpeng@iscas.ac.cn> Content-Language: en-US From: R Nageswara Sastry In-Reply-To: <20260401160316.88551-1-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: CUynIvg6OF1Okb36_nayh_yPMFqePo9P X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDIyMDA0NiBTYWx0ZWRfX53Lr7Dg/apNb 02wGc1+uD6SzfK9fAEyhpR2Dc/m2zz9WzDOxgJ8k/sdWq3PqQHYSXsE7SJ8bj3fbm6kZiWuBJRr 7sj3m0nbOiAemjHYRQBYUTH/3m+G+/TEdcfoIiWm0VrAsPFwIu5DAuLhGR0tDpsaQgBFPevHJbU XtHXWnSQMbcdmjZMT3zSLi9lXCF7VoB2KzSC1+p0zg6v3n2H6+d6miTHgACN+vsWF0lTZIUgUdj lr5+ISSZaNVxhSfUmqIy7er6qXG4S9VhrUbyDXJarMAbgcZ3I9pvjbmu4Xw6bjOlmL0pE0gJMCb LXFnpboVJWtOVNLA3UA7iREiRvjSDuQRQuf5Q/sYO73h9sFZyCJMcucZ0SWPk5+L1ga7evOhHI0 NnLiZabXJS67dYeAYiKwqqvTviRfey/Kj7cH2UYzcjc1FDWrGjBBGZooXBADEZa2PRKnJ9ZmX6P UlmFy/KFKOeD62Czq3g== X-Authority-Analysis: v=2.4 cv=a6kAM0SF c=1 sm=1 tr=0 ts=69e85362 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VnNF1IyMAAAA:8 a=T8gcFfjw_zj36hfkXUkA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: fvridPnHijkGuQZXFXKX3aThw3_XIlYE 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=2026-04-21_03,2026-04-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 suspectscore=0 spamscore=0 adultscore=0 bulkscore=0 lowpriorityscore=0 impostorscore=0 clxscore=1011 phishscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2604220046 On 01.04.2026 9:33 PM, Pengpeng Hou wrote: > parse_system_parameter_string() reads the shared processor LPAR > attributes into a firmware buffer that can hold up to 4000 bytes, but it > still tokenizes that payload through a fixed 1026-byte scratch buffer. A > single long key-value fragment can therefore overrun the local parser > buffer before the next comma delimiter is seen. > > Allocate the scratch buffer to the current payload size so tokenization > stays within bounds. > > Fixes: fff9846be00c ("powerpc/pseries/lparcfg: convert to papr_sysparm API") > Signed-off-by: Pengpeng Hou > --- Tested-by: R Nageswara Sastry Tested with different sizes of the buffer namely 1000, 1026, 1500, 2000, 3900, 4000, 1027, 3500 with a sample test kernel module. Using the same module injected the text with the above sizes in to lparcfg Example: system_potential_processors=8HIJKLMN...GHIJK > arch/powerpc/platforms/pseries/lparcfg.c | 23 +++++++++++++---------- > 1 file changed, 13 insertions(+), 10 deletions(-) > > diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c > index 8821c378bfff..c09f474c241e 100644 > --- a/arch/powerpc/platforms/pseries/lparcfg.c > +++ b/arch/powerpc/platforms/pseries/lparcfg.c > @@ -385,8 +385,6 @@ static void read_lpar_name(struct seq_file *m) > read_dt_lpar_name(m); > } > > -#define SPLPAR_MAXLENGTH 1026*(sizeof(char)) > - > /* > * parse_system_parameter_string() > * Retrieve the potential_processors, max_entitled_capacity and friends > @@ -407,27 +405,32 @@ static void parse_system_parameter_string(struct seq_file *m) > const char *local_buffer; > int splpar_strlen; > int idx, w_idx; > - char *workbuffer = kzalloc(SPLPAR_MAXLENGTH, GFP_KERNEL); > - > - if (!workbuffer) > - goto out_free; > + size_t workbuf_size; > + char *workbuffer; > > splpar_strlen = be16_to_cpu(buf->len); > local_buffer = buf->val; > + workbuf_size = splpar_strlen + 1; > + > + workbuffer = kzalloc(workbuf_size, GFP_KERNEL); > + if (!workbuffer) > + goto out_free; > > w_idx = 0; > idx = 0; > - while ((*local_buffer) && (idx < splpar_strlen)) { > + while ((idx < splpar_strlen) && local_buffer[idx]) { > workbuffer[w_idx++] = local_buffer[idx++]; > - if ((local_buffer[idx] == ',') > + if (idx >= splpar_strlen || > + (local_buffer[idx] == ',') > || (local_buffer[idx] == '\0')) { > workbuffer[w_idx] = '\0'; > if (w_idx) { > /* avoid the empty string */ > seq_printf(m, "%s\n", workbuffer); > } > - memset(workbuffer, 0, SPLPAR_MAXLENGTH); > - idx++; /* skip the comma */ > + memset(workbuffer, 0, workbuf_size); > + if (idx < splpar_strlen) > + idx++; /* skip the comma */ > w_idx = 0; > } else if (local_buffer[idx] == '=') { > /* code here to replace workbuffer contents -- Thanks and Regards R.Nageswara Sastry