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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, ast@kernel.org,
	andrii.nakryiko@gmail.com, john.fastabend@gmail.com
Subject: Re: [PATCH bpf-next v3 0/8] Fix BPF probe memory helpers
Date: Sat, 2 Nov 2019 13:08:52 -0700
Message-ID: <20191102200850.cyf3ql5ao43p7vmz@ast-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <cover.1572649915.git.daniel@iogearbox.net>

On Sat, Nov 02, 2019 at 12:17:55AM +0100, Daniel Borkmann wrote:
> This set adds probe_read_{user,kernel}(), probe_read_str_{user,kernel}()
> helpers, fixes probe_write_user() helper and selftests. For details please
> see individual patches.
> 
> Thanks!
> 
> v2 -> v3:
>   - noticed two more things that are fixed in here:
>    - bpf uapi helper description used 'int size' for *_str helpers, now u32
>    - we need TASK_SIZE_MAX + guard page on x86-64 in patch 2 otherwise
>      we'll trigger the 00c42373d397 warn as well, so full range covered now

Applied and I wish I could say: "queued up for -stable".

The warning added by
commit 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences")
dumps the stack trace that looks like kernel panic.  It was reported numerous
times by scared users and crash detection tools. Until now bpf tracing
programs couldn't be fixed to avoid that warning. This patch set is a big step
forward solving user vs kernel access issue. User space tool 'bpftrace'
provisioned language feature 'kaddr' and 'uaddr' in anticipation of the
bpf_probe_read_user() helper.
Thank you Daniel for implementing this fix.

      parent reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-01 23:17 Daniel Borkmann
2019-11-01 23:17 ` [PATCH bpf-next v3 1/8] uaccess: Add non-pagefault user-space write function Daniel Borkmann
2019-11-01 23:17 ` [PATCH bpf-next v3 2/8] uaccess: Add strict non-pagefault kernel-space read function Daniel Borkmann
2019-11-01 23:17 ` [PATCH bpf-next v3 3/8] bpf: Make use of probe_user_write in probe write helper Daniel Borkmann
2019-11-01 23:17 ` [PATCH bpf-next v3 4/8] bpf: Add probe_read_{user,kernel} and probe_read_{user,kernel}_str helpers Daniel Borkmann
2019-11-01 23:18 ` [PATCH bpf-next v3 5/8] bpf: Switch BPF probe insns to bpf_probe_read_kernel Daniel Borkmann
2019-11-01 23:18 ` [PATCH bpf-next v3 6/8] bpf, samples: Use bpf_probe_read_user where appropriate Daniel Borkmann
2019-11-01 23:18 ` [PATCH bpf-next v3 7/8] bpf, testing: Convert prog tests to probe_read_{user,kernel}{,_str} helper Daniel Borkmann
2019-11-01 23:18 ` [PATCH bpf-next v3 8/8] bpf, testing: Add selftest to read/write sockaddr from user space Daniel Borkmann
2019-11-02 20:08 ` Alexei Starovoitov [this message]

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