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Groups > linux.kernel > #1284247
| From | David Miller <davem@davemloft.net> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: bpf: undefined shift in __bpf_prog_run |
| Date | 2015-12-04 22:40 +0100 |
| Message-ID | <qC6f8-88D-5@gated-at.bofh.it> (permalink) |
| References | <qC4dk-6SH-17@gated-at.bofh.it> <qC4wF-6ZX-3@gated-at.bofh.it> <qC5j4-7wJ-21@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
From: Alexei Starovoitov <alexei.starovoitov@gmail.com> Date: Fri, 4 Dec 2015 12:35:23 -0800 > On Fri, Dec 04, 2015 at 08:48:57PM +0100, Dmitry Vyukov wrote: >> >> For example, a compiler can assume that result of left shift is larger >> or equal to first operand, which in turn can allow it to elide some >> bounds check in code, which in turn can lead to an exploit. I am not >> saying that this particular pattern is present in the code, what I >> want to say is that such undefined behaviors can lead to very >> unpredictable and unexpected consequences. > > Within bpf it cannot. > shift is not used in any memory or bounds operations. > so reg <<= 1234 cannot be exploited. +1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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bpf: undefined shift in __bpf_prog_run Dmitry Vyukov <dvyukov@google.com> - 2015-12-04 12:20 +0100
Re: bpf: undefined shift in __bpf_prog_run Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2015-12-04 19:50 +0100
Re: bpf: undefined shift in __bpf_prog_run Dmitry Vyukov <dvyukov@google.com> - 2015-12-04 20:10 +0100
Re: bpf: undefined shift in __bpf_prog_run Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2015-12-04 20:20 +0100
Re: bpf: undefined shift in __bpf_prog_run David Miller <davem@davemloft.net> - 2015-12-04 20:30 +0100
Re: bpf: undefined shift in __bpf_prog_run Dmitry Vyukov <dvyukov@google.com> - 2015-12-04 20:50 +0100
Re: bpf: undefined shift in __bpf_prog_run Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2015-12-04 21:40 +0100
Re: bpf: undefined shift in __bpf_prog_run Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2015-12-04 22:00 +0100
Re: bpf: undefined shift in __bpf_prog_run David Miller <davem@davemloft.net> - 2015-12-04 22:40 +0100
Re: bpf: undefined shift in __bpf_prog_run Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-12-04 22:30 +0100
RE: bpf: undefined shift in __bpf_prog_run David Laight <David.Laight@ACULAB.COM> - 2015-12-07 12:20 +0100
Re: bpf: undefined shift in __bpf_prog_run Daniel Borkmann <daniel@iogearbox.net> - 2015-12-09 19:40 +0100
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