netdev - Re: [PATCH bpf-next v2] bpf, seccomp: fix false positive preemption splat for cbpf->ebpf progs

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Message-ID: <20190220235952.uzrsjypoqkha7ya6@ast-mbp.dhcp.thefacebook.com>
Date:   Wed, 20 Feb 2019 15:59:54 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     ast@...nel.org, keescook@...omium.org, netdev@...r.kernel.org
Subject: Re: [PATCH bpf-next v2] bpf, seccomp: fix false positive preemption
 splat for cbpf->ebpf progs

On Thu, Feb 21, 2019 at 12:01:35AM +0100, Daniel Borkmann wrote:
> In 568f196756ad ("bpf: check that BPF programs run with preemption disabled")
> a check was added for BPF_PROG_RUN() that for every invocation preemption is
> disabled to not break eBPF assumptions (e.g. per-cpu map). Of course this does
> not count for seccomp because only cBPF -> eBPF is loaded here and it does
> not make use of any functionality that would require this assertion. Fix this
> false positive by adding and using SECCOMP_RUN() variant that does not have
> the cant_sleep(); check.
> 
> Fixes: 568f196756ad ("bpf: check that BPF programs run with preemption disabled")
> Reported-by: syzbot+8bf19ee2aa580de7a2a7@...kaller.appspotmail.com
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> Acked-by: Kees Cook <keescook@...omium.org>

Applied, Thanks