lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Thu, 28 Feb 2019 09:06:54 +0100
From:   Vlastimil Babka <>
To:     Oscar Salvador <>,
        Andrew Morton <>
Subject: Re: [PATCH] mm,mremap: Bail out earlier in mremap_to under map

On 2/27/19 10:32 PM, Oscar Salvador wrote:
> On Tue, Feb 26, 2019 at 02:04:28PM -0800, Andrew Morton wrote:
>> How is this going to affect existing userspace which is aware of the
>> current behaviour?
> Well, current behavior is not really predictable.
> Our customer was "surprised" that the call to mremap() failed, but the regions
> got unmapped nevertheless.
> They found it the hard way when they got a segfault when trying to write to those
> regions when cleaning up. 
> As I said in the changelog, the possibility for false positives exists, due to
> the fact that we might get rid of several vma's when unmapping, but I do not
> expect existing userspace applications to start failing.
> Should be that the case, we can revert the patch, it is not that it adds a lot
> of churn.

Hopefully the only program that would start failing would be a LTP test
testing the current behavior near the limit (if such test exists). And
that can be adjusted.

>> And how does it affect your existing cleanup code, come to that?  Does
>> it work as well or better after this change?
> I guess the customer can trust more reliable that the maps were left untouched.
> I still have my reserves though.
> We can get as far as move_vma(), and copy_vma() can fail returning -ENOMEM.
> (Or not due to the "too small to fail" ?)

Powered by blists - more mailing lists