lists.openwall.net   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  linux-hardening  linux-cve-announce  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]
Message-ID: <d5137f25846ebf585383de4d994d388eabab9d60.camel@linux.ibm.com>
Date: Mon, 04 Nov 2024 11:07:38 +0100
From: Ilya Leoshkevich <iii@...ux.ibm.com>
To: Hou Tao <houtao@...weicloud.com>, Byeonguk Jeong <jungbu2855@...il.com>
Cc: andrii@...nel.org, daniel@...earbox.net, martin.lau@...ux.dev,
        Alexei
 Starovoitov <ast@...nel.org>, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf] selftests/bpf: Add a copyright notice to
 lpm_trie_map_get_next_key

On Mon, 2024-11-04 at 09:34 +0800, Hou Tao wrote:
> Hi,
> 
> On 11/3/2024 2:04 PM, Byeonguk Jeong wrote:
> > Hi,
> > 
> > The selftest "verifier_bits_iter/bad words" has been failed with
> > retval 115, while I did not touched anything but a comment.
> > 
> > Do you have any idea why it failed? I am not sure whether it
> > indicates
> > any bugs in the kernel.
> > 
> > Best,
> > Byeonguk
> 
> Sorry for the inconvenience. It seems the test case
> "verifier_bits_iter/bad words" is flaky. It may fail randomly, such
> as
> in [1]. I think calling bpf_probe_read_kernel_common() on 3GB addr
> under
> s390 host may succeed and the content of the memory address will
> decide
> whether the test case will succeed or not. Do not know the reason why
> reading 3GB address succeeds under s390. Hope to get some insight
> from
> Ilya.  I think we could fix the failure first by using NULL as the
> address of bad words just like null_pointer test case does. Will
> merge
> the test in bad_words into the null_pointer case.

Hi,

s390 kernel runs in a completely separate address space, there is no
user/kernel split at TASK_SIZE. The same address may be valid in both
the kernel and the user address spaces, there is no way to tell by
looking at it. The config option related to this property is
ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.

Also, unfortunately, 0 is a valid address in the s390 kernel address
space.

I wonder if we could use -4095 as an address that cannot be
dereferenced on all platforms?

Best regards,
Ilya

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ