From: Puranjay Mohan <puranjay12@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
David Ahern <dsahern@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
X86 ML <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
Jean-Philippe Brucker <jean-philippe@linaro.org>,
Network Development <netdev@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
Ilya Leoshkevich <iii@linux.ibm.com>
Subject: Re: [PATCH bpf v5] bpf: verifier: prevent userspace memory access
Date: Sun, 24 Mar 2024 19:34:56 +0000 [thread overview]
Message-ID: <mb61pwmprbezj.fsf@gmail.com> (raw)
In-Reply-To: <CAADnVQKW2ajQ25BkOO_D2=N2wOHt9fdNY+tWRunXe_sN-w+33g@mail.gmail.com>
Alexei Starovoitov <alexei.starovoitov@gmail.com> writes:
> On Sun, Mar 24, 2024 at 11:54 AM Puranjay Mohan <puranjay12@gmail.com> wrote:
>>
>> +u64 bpf_arch_uaddress_limit(void)
>> +{
>> + return max(TASK_SIZE_MAX + PAGE_SIZE, VSYSCALL_ADDR);
>
> This is broken. See my other email.
> Sadly you didn't test it.
Yes, sorry for this. I was relying on the CI for the test this time as
thought it would work. I just realised this would reject all addresses!
Given that the current x86-64 JIT just tests for TASK_SIZE_MAX +
PAGE_SIZE can we go ahead with this and later fix it for VSYSCALL_ADDR
as it is specific for x86-64?
Also, I will spend some time figuring out the best way to do this, there
should be some mathematical trick somewhere.
next prev parent reply other threads:[~2024-03-24 19:35 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-24 18:53 [PATCH bpf v5] bpf: verifier: prevent userspace memory access Puranjay Mohan
2024-03-24 19:13 ` Alexei Starovoitov
2024-03-24 19:34 ` Puranjay Mohan [this message]
2024-03-24 20:47 ` Alexei Starovoitov
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