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From: Eduard Zingerman <eddyz87@gmail.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org,
	daniel@iogearbox.net,  martin.lau@linux.dev, kernel-team@fb.com,
	yonghong.song@linux.dev,  memxor@gmail.com, awerner32@gmail.com
Subject: Re: [PATCH bpf 12/12] selftests/bpf: check if max number of bpf_loop iterations is tracked
Date: Fri, 17 Nov 2023 20:53:32 +0200	[thread overview]
Message-ID: <6da7c6b9617663daa54ed27d2c1637cc71dfb7a3.camel@gmail.com> (raw)
In-Reply-To: <CAEf4BzYd_Dv4fEoPe+n+sRXxHFmYrTs7w45jtYeQByNH521gzA@mail.gmail.com>

On Fri, 2023-11-17 at 11:47 -0500, Andrii Nakryiko wrote:
[...]
> > +SEC("?raw_tp")
> > +__success __log_level(2)
> > +/* Check that last verified exit from the program visited each
> > + * callback expected number of times: one visit per callback for each
> > + * top level bpf_loop call.
> > + */
> > +__msg("r1 = *(u64 *)(r10 -16)       ; R1_w=111111 R10=fp0 fp-16=111111")
> > +/* Ensure that read above is the last one by checking that there are
> > + * no more reads for ctx.i.
> > + */
> > +__not_msg("r1 = *(u64 *)(r10 -16)      ; R1_w=")
> 
> can't you enforce that we don't go above 111111 just by making sure to
> use r1 - 111111 + 1 as an index into choice_arr()?
> 
> We can then simplify the patch set by dropping __not_msg() parts (and
> can add them separately).

Well, r1 could be 0 as well, so idx would be out of bounds.
But I like the idea, it is possible to check that r1 is either 00000,
100000, ..., 111111 and do something unsafe otherwise.
Thank you. I'll drop __not_msg() then.



  reply	other threads:[~2023-11-17 18:53 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-16  2:17 [PATCH bpf 00/12] verify callbacks as if they are called unknown number of times Eduard Zingerman
2023-11-16  2:17 ` [PATCH bpf 01/12] selftests/bpf: track tcp payload offset as scalar in xdp_synproxy Eduard Zingerman
2023-11-17 16:46   ` Andrii Nakryiko
2023-11-16  2:17 ` [PATCH bpf 02/12] selftests/bpf: track string payload offset as scalar in strobemeta Eduard Zingerman
2023-11-17 16:46   ` Andrii Nakryiko
2023-11-17 18:52     ` Eduard Zingerman
2023-11-16  2:17 ` [PATCH bpf 03/12] selftests/bpf: fix bpf_loop_bench for new callback verification scheme Eduard Zingerman
2023-11-17 16:46   ` Andrii Nakryiko
2023-11-17 18:52     ` Eduard Zingerman
2023-11-17 21:38   ` Alexei Starovoitov
2023-11-17 21:43     ` Eduard Zingerman
2023-11-17 21:47       ` Alexei Starovoitov
2023-11-17 21:50         ` Eduard Zingerman
2023-11-17 21:55           ` Alexei Starovoitov
2023-11-16  2:17 ` [PATCH bpf 04/12] bpf: extract __check_reg_arg() utility function Eduard Zingerman
2023-11-17 16:46   ` Andrii Nakryiko
2023-11-16  2:17 ` [PATCH bpf 05/12] bpf: extract setup_func_entry() " Eduard Zingerman
2023-11-17 16:46   ` Andrii Nakryiko
2023-11-17 18:52     ` Eduard Zingerman
2023-11-16  2:17 ` [PATCH bpf 06/12] bpf: verify callbacks as if they are called unknown number of times Eduard Zingerman
2023-11-17 16:46   ` Andrii Nakryiko
2023-11-17 18:52     ` Eduard Zingerman
2023-11-17 20:27       ` Andrii Nakryiko
2023-11-17 21:03         ` Eduard Zingerman
2023-11-16  2:17 ` [PATCH bpf 07/12] selftests/bpf: tests for iterating callbacks Eduard Zingerman
2023-11-17 16:46   ` Andrii Nakryiko
2023-11-16  2:17 ` [PATCH bpf 08/12] bpf: widening for callback iterators Eduard Zingerman
2023-11-17 16:46   ` Andrii Nakryiko
2023-11-16  2:18 ` [PATCH bpf 09/12] selftests/bpf: test widening for iterating callbacks Eduard Zingerman
2023-11-17 16:47   ` Andrii Nakryiko
2023-11-17 18:53     ` Eduard Zingerman
2023-11-17 20:28       ` Andrii Nakryiko
2023-11-16  2:18 ` [PATCH bpf 10/12] bpf: keep track of max number of bpf_loop callback iterations Eduard Zingerman
2023-11-16 14:08   ` Andrii Nakryiko
2023-11-16 14:13     ` Eduard Zingerman
2023-11-17 16:47   ` Andrii Nakryiko
2023-11-17 18:53     ` Eduard Zingerman
2023-11-17 20:30       ` Andrii Nakryiko
2023-11-16  2:18 ` [PATCH bpf 11/12] selftests/bpf: add __not_msg annotation for test_loader based tests Eduard Zingerman
2023-11-17 16:45   ` Andrii Nakryiko
2023-11-17 18:53     ` Eduard Zingerman
2023-11-17 20:31       ` Andrii Nakryiko
2023-11-17 21:10         ` Eduard Zingerman
2023-11-17 21:33           ` Alexei Starovoitov
2023-11-16  2:18 ` [PATCH bpf 12/12] selftests/bpf: check if max number of bpf_loop iterations is tracked Eduard Zingerman
2023-11-17 16:47   ` Andrii Nakryiko
2023-11-17 18:53     ` Eduard Zingerman [this message]
2023-11-17 20:32       ` Andrii Nakryiko
2023-11-17 21:18         ` Eduard Zingerman

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