arm32 binaries work with CONFIG_COMPAT as root but not as user?

[Riku Voipio]

On 28 January 2015 at 13:47, Catalin Marinas <catalin.marinas at arm.com> wrote:
> On Wed, Jan 28, 2015 at 11:42:55AM +0000, Riku Voipio wrote:
>> On 28 January 2015 at 13:22, Catalin Marinas <catalin.marinas at arm.com> wrote:
>> > On Wed, Jan 28, 2015 at 10:52:21AM +0000, Riku Voipio wrote:
>> > What does this say:
>> cat /proc/sys/vm/mmap_min_addr
>> 65536
>>
>> > # cat /proc/sys/vm/mmap_min_addr
>> >
>> > If it is 64K, it won't run 32-bit apps as non-root.
>>
>> echo 32768 > /proc/sys/vm/mmap_min_addr
>>
>> and indeed binaries work as expected.
>>
>> The ubuntu LTS 3.13 kernel has:
>>
>> /boot/config-3.13.0-39-generic:CONFIG_DEFAULT_MMAP_MIN_ADDR=65536
>>
>> I need to check how the value ended up wrong on the 3.19-rc3 I tested.
>
> It may be set by some boot script on arm64 Ubuntu (so entirely in user
> space).

Correct, the invalid value is set in /etc/sysctl.d/10-zeropage.conf.
I've also opened a bug for the ubuntu folk to fix.

https://bugs.launchpad.net/ubuntu/+source/procps/+bug/1415481

Riku