From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Paul Menzel <pmenzel@molgen.mpg.de>,
"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
Sandipan Das <sandipan@linux.ibm.com>
Cc: it+linux-bpf@molgen.mpg.de, netdev@vger.kernel.org,
bpf@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: sysctl: setting key "net.core.bpf_jit_enable": Invalid argument
Date: Sun, 11 Apr 2021 18:23:44 +0200 [thread overview]
Message-ID: <d880c38c-e410-0b69-0897-9cbf4b759045@csgroup.eu> (raw)
In-Reply-To: <412d88b2-fa9a-149e-6f6e-3cfbce9edef0@molgen.mpg.de>
Le 11/04/2021 à 13:09, Paul Menzel a écrit :
> Dear Linux folks,
>
>
> Related to * [CVE-2021-29154] Linux kernel incorrect computation of branch displacements in BPF JIT
> compiler can be abused to execute arbitrary code in Kernel mode* [1], on the POWER8 system IBM
> S822LC with self-built Linux 5.12.0-rc5+, I am unable to disable `bpf_jit_enable`.
>
> $ /sbin/sysctl net.core.bpf_jit_enable
> net.core.bpf_jit_enable = 1
> $ sudo /sbin/sysctl -w net.core.bpf_jit_enable=0
> sysctl: setting key "net.core.bpf_jit_enable": Invalid argument
>
> It works on an x86 with Debian sid/unstable and Linux 5.10.26-1.
Maybe you have selected CONFIG_BPF_JIT_ALWAYS_ON in your self-built kernel ?
config BPF_JIT_ALWAYS_ON
bool "Permanently enable BPF JIT and remove BPF interpreter"
depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
help
Enables BPF JIT and removes BPF interpreter to avoid
speculative execution of BPF instructions by the interpreter
Christophe
next prev parent reply other threads:[~2021-04-11 16:24 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-11 11:09 sysctl: setting key "net.core.bpf_jit_enable": Invalid argument Paul Menzel
2021-04-11 16:23 ` Christophe Leroy [this message]
2021-04-11 18:39 ` Paul Menzel
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