Re: [PATCH] s390x/ipl: check kernel command line size

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 10/11/21 15:38, Thomas Huth wrote:
> On 06/10/2021 11.26, Marc Hartmayer wrote:
>> Check if the provided kernel command line exceeds the maximum size of
>> the s390x
>> Linux kernel command line size, which is 896 bytes.
>>
>> Reported-by: Sven Schnelle <svens@linux.ibm.com>
>> Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
>> ---
>>   hw/s390x/ipl.c | 12 +++++++++++-
>>   1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
>> index 1821c6faeef3..a58ea58cc736 100644
>> --- a/hw/s390x/ipl.c
>> +++ b/hw/s390x/ipl.c
>> @@ -38,6 +38,7 @@
>>   #define KERN_IMAGE_START                0x010000UL
>>   #define LINUX_MAGIC_ADDR                0x010008UL
>>   #define KERN_PARM_AREA                  0x010480UL
>> +#define KERN_PARM_AREA_SIZE             0x000380UL
>>   #define INITRD_START                    0x800000UL
>>   #define INITRD_PARM_START               0x010408UL
>>   #define PARMFILE_START                  0x001000UL
>> @@ -190,10 +191,19 @@ static void s390_ipl_realize(DeviceState *dev,
>> Error **errp)
>>            * loader) and it won't work. For this case we force it to
>> 0x10000, too.
>>            */
>>           if (pentry == KERN_IMAGE_START || pentry == 0x800) {
>> -            char *parm_area = rom_ptr(KERN_PARM_AREA,
>> strlen(ipl->cmdline) + 1);
>> +            size_t cmdline_size = strlen(ipl->cmdline) + 1;
>> +            char *parm_area = rom_ptr(KERN_PARM_AREA, cmdline_size);
>> +
>>               ipl->start_addr = KERN_IMAGE_START;
>>               /* Overwrite parameters in the kernel image, which are
>> "rom" */
>>               if (parm_area) {
>> +                if (cmdline_size > KERN_PARM_AREA_SIZE) {
>> +                    error_setg(errp,
>> +                               "kernel command line exceeds maximum
>> size: %lu > %lu",
> 
> I think the first %lu should be %zd instead?

%zu ;)

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> 
> Apart from that, the patch looks fine to me... so if you agree, I can
> fix that up when picking up the patch.
> 
>  Thomas