On 2013年04月24日 14:28, Vasant Hegde wrote:
> On 04/23/2013 08:42 AM, Chen Gang wrote:
>>
>> need set '\0' for 'local_buffer'.
>>
>> SPLPAR_MAXLENGTH is 1026, RTAS_DATA_BUF_SIZE is 4096. so the contents of
>> rtas_data_buf may truncated in memcpy.
>>
>> if contents are really truncated.
>> the splpar_strlen is more than 1026. the next while loop checking will
>> not find the end of buffer. that will cause memory access violation.
>>
>
> Per parameter length in ibm,get-system-parameter RTAS call is limited to
> 1026 bytes (1024 bytes of data + 2 bytes length). And 'rtas_data_buf'
> was set to 0 (first 1026 bytes) before call RTAS call. At the worst if
> we get junk in RTAS output length field helps to exit from the while
> loop. So I don't think we need this patch.
Is get-system-parameter return the NUL terminated string ? if so, it
will no issue (just like your discription).
If it will not return NUL terminated string, please see line 326:
"while ((*local_buffer) && (idx < splpar_strlen))"
(when idx == 1024, *local_buffer is memory access violation).
Since we use the first 2 bytes as length, and also be sure of the real
length will never more than 1024, I suggest to:
---------------------------patch begin--------------------------------
diff --git a/arch/powerpc/kernel/lparcfg.c b/arch/powerpc/kernel/lparcfg.c
index 801a757..f8bd7cf 100644
--- a/arch/powerpc/kernel/lparcfg.c
+++ b/arch/powerpc/kernel/lparcfg.c
@@ -323,7 +323,7 @@ static void parse_system_parameter_string(struct seq_file
*m)
w_idx = 0;
idx = 0;
- while ((*local_buffer) && (idx < splpar_strlen)) {
+ while (idx < splpar_strlen) {
workbuffer[w_idx++] = local_buffer[idx++];
if ((local_buffer[idx] == ',')
|| (local_buffer[idx] == '\0')) {
---------------------------patch end----------------------------------
Thanks.
--
Chen Gang
Asianux Corporation
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
