Re: [PATCH v2] lzo: fix ip overrun during compress.

Yueyi Li
2018-12-18T09:25:48Z

Hi Markus & Kees,

On 2018/12/17 0:56, Markus F.X.J. Oberhumer wrote:
> Yueyi,
>
> if ASLR does indeed exclude the last page (like it should), how do
> you get the invalid (0xfffffffffffff000, 4096) mapping then?
Regarding following code, seems ASLR is align to ARM64_MEMSTART_ALIGN,I
don`t think it will exclude the top 4K address space.

```
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
extern u16 memstart_offset_seed;
u64 range = linear_region_size -
(bootloader_memory_limit - memblock_start_of_DRAM());

/*
* If the size of the linear region exceeds, by a sufficient
* margin, the size of the region that the available physical
* memory spans, randomize the linear region as well.
*/
if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
range = range / ARM64_MEMSTART_ALIGN + 1;
memstart_addr -= ARM64_MEMSTART_ALIGN *
((range * memstart_offset_seed) >> 16);
}
}
```

Thanks,
Yueyi