Re: [PATCH 03/15] hw/alpha/dp264: Validate kernel and initrd sizes

[Yodel Eldar <yodel.eldar@yodel.dev>]

Hi, Richard

On 25/03/2026 19:11, Richard Henderson wrote:
> On 3/11/26 08:31, Yodel Eldar wrote:
>> @@ -192,7 +192,15 @@ static void clipper_init(MachineState *machine)
>>               }
>>               /* Put the initrd image as high in memory as possible.  */
>> -            initrd_base = (ram_size - initrd_size) & TARGET_PAGE_MASK;
>> +            if (usub64_overflow(ram_size, initrd_size, &initrd_base)) {
>> +                error_report("initial ram disk exceeds allotted ram 
>> size");
>> +                exit(1);
>> +            }
>> +            initrd_base &= TARGET_PAGE_MASK;
>> +            if (initrd_base <= kernel_high) {
>> +                warn_report("initial ram disk overlaps with kernel");
>> +            }
> 
> Why is the first an error and the second a warning?
> 

Initially, I had both as fatal, but then I figured a (mis)adventurous
user may actually want to experiment with kernel/initrd overlap, whereas
an underflow is something we can't allow (and initrd being larger than
RAM is physically impossible AFAIK). I could make the overlap fatal,
too, if that's better?

Thanks for the reviews in Patches 1-2, and for letting me know about
using cpu_to_le64 in Patch 4. v2 has seen some nontrivial changes in
the later patches, and I'll be sending it soon.

Thanks again,
Yodel

> 
> r~
>