[PATCH 2/2] x86/mmap: handle worst-case heap randomization in mmap_base

Saidi, Ali alisaidi at amazon.com
Sun Mar 17 08:52:08 PDT 2019



> On Mar 13, 2019, at 11:26 AM, Dave Hansen <dave.hansen at intel.com> wrote:
> 
>> On 3/12/19 10:32 AM, Ali Saidi wrote:
>> +    /* Provide space for brk randomization */
>> +    pad += SZ_32M;
> 
> Just curious:  Why is the padding in your other patch conditional on the
> 32-bit vs. 64-bit apps, but here it's always 32M?
Arm changes the amount of brk based on the process being 32 vs 64 bit. X86 doesn’t appear to do this. 
> 
> Also, did you hit this problem in practice somehow?

Just debugging a crash when testing a version of a library I compiled. 

Ali


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