From: Daniel Borkmann <daniel@iogearbox.net>
To: Ilya Leoshkevich <iii@linux.ibm.com>,
Alexei Starovoitov <ast@kernel.org>
Cc: bpf@vger.kernel.org, Andrey Ignatov <rdna@fb.com>,
Yonghong Song <yhs@fb.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>
Subject: Re: [PATCH bpf v2] bpf: fix accessing bpf_sysctl.file_pos on s390
Date: Mon, 16 Sep 2019 12:11:03 +0200 [thread overview]
Message-ID: <0e48ebeb-2538-8394-32cb-d4a4aa339cda@iogearbox.net> (raw)
In-Reply-To: <20190816105300.49035-1-iii@linux.ibm.com>
On 8/16/19 12:53 PM, Ilya Leoshkevich wrote:
> "ctx:file_pos sysctl:read write ok" fails on s390 with "Read value !=
> nux". This is because verifier rewrites a complete 32-bit
> bpf_sysctl.file_pos update to a partial update of the first 32 bits of
> 64-bit *bpf_sysctl_kern.ppos, which is not correct on big-endian
> systems.
>
> Fix by using an offset on big-endian systems.
>
> Ditto for bpf_sysctl.file_pos reads. Currently the test does not detect
> a problem there, since it expects to see 0, which it gets with high
> probability in error cases, so change it to seek to offset 3 and expect
> 3 in bpf_sysctl.file_pos.
>
> Fixes: e1550bfe0de4 ("bpf: Add file_pos field to bpf_sysctl ctx")
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Applied, thanks!
prev parent reply other threads:[~2019-09-16 10:44 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-16 10:53 [PATCH bpf v2] bpf: fix accessing bpf_sysctl.file_pos on s390 Ilya Leoshkevich
2019-08-16 15:43 ` Yonghong Song
2019-09-03 22:13 ` Daniel Borkmann
2019-09-04 13:53 ` Ilya Leoshkevich
2019-09-08 3:37 ` Andrey Ignatov
2019-09-16 10:11 ` Daniel Borkmann [this message]
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