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Wed, 22 Apr 2026 04:49:37 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (smtpav01.fra02v.mail.ibm.com [10.20.54.100]) by smtprelay05.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 63M4nYg745351244 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 22 Apr 2026 04:49:34 GMT Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0307720043; Wed, 22 Apr 2026 04:49:34 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 64D5320040; 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 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/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; 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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