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[176.36.0.241]) by smtp.gmail.com with ESMTPSA id d24-20020ac241d8000000b0050089b26eb0sm526120lfi.132.2023.10.04.02.49.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Oct 2023 02:49:57 -0700 (PDT) Message-ID: Subject: Re: [BUG] verifier escape with iteration helpers (bpf_loop, ...) From: Eduard Zingerman To: Alexei Starovoitov Cc: Andrii Nakryiko , Andrew Werner , bpf , Andrei Matei , Tamir Duberstein , Joanne Koong , kernel-team@dataexmachina.dev, Song Liu , Kumar Kartikeya Dwivedi Date: Wed, 04 Oct 2023 12:49:55 +0300 In-Reply-To: References: <9dd331b31755632f0528bfb1d0acbf904cedbd98.camel@gmail.com> <680e69504eabbae2abd5e9e2b745319c561c86ef.camel@gmail.com> <8b75e01d27696cd6661890e49bdc06b1e96092c7.camel@gmail.com> <5b7f4b6199decf266a9218b674c232662ed13db5.camel@gmail.com> <20231003230820.iazvofhysfmurwon@MacBook-Pro-49.local> <3d88ede5cbe38ae96be0c148770454b2344fdcce.camel@gmail.com> <20231004025731.ft7xjnr2nxdhxjq5@MacBook-Pro-49.local> Autocrypt: addr=eddyz87@gmail.com; prefer-encrypt=mutual; keydata=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 nYzhLWGcczc6J71q1Dje0l5vIPaSFOgwmWD4DA+WvuxM/shH4rtWeodbv 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 t1iq+gsfnXbPz5AnS598ScZI1oP7OrPSFJkt/z4acEbOQDQs8aUqrd46PV jsdqGvKnXZxzylux29UTNby4jTlz9pNJM+wPrDRmGfchLDUmf6CffaUYCbu4FiId+9+dcTCDvxbABRy1C3OJ8QY7cxfJ+pEZW18fRJ0XCl/fiV/ecAOfB3HsqgTzAn555h0rkFgay0hAvMU/mAW/CFNSIxV397zm749ZNLA0L2dMy1AKuOqH+/B+/ImBfJMDjmdyJQ8WU/OFRuGLdqOd2oZrA1iuPIa+yUYyZkaZfz/emQwpIL1+Q4p1R/OplA4yc301AqruXXUcVDbEB+joHW3hy5FwK5t5OwTKatrSJBkydSF9zdXy98fYzGniRyRA65P0Ix/8J3BYB4edY2/w0Ip/mdYsYQljBY0A== Content-Type: multipart/mixed; boundary="=-I7sf5AKhnRvgCYTyaHin" User-Agent: Evolution 3.50.0 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-1.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_ENVFROM_END_DIGIT, FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net --=-I7sf5AKhnRvgCYTyaHin Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2023-10-03 at 22:50 -0700, Alexei Starovoitov wrote: > On Tue, Oct 3, 2023 at 7:57=E2=80=AFPM Alexei Starovoitov > wrote: > >=20 > > ok. discard that idea. >=20 > Attached is a 3rd version of the same idea I argued earlier. > Let normal DFS go as normal, > do states_equal() on V which has 1 looping branch remain > and all other explored. > To achieve that when iter_next() is seen do parent->looping_states +=3D 2= ; >=20 > then when processing any children do parent->looping_states++; > in the correct parent. > Since there could be many intermediate states have to walk back > parentage chain to increment correct parent. > When the state reaches bpf_exit or safety, walk back > the parentage chain and do looping_states--. > The state is ok to use in states_equal() if looping_states=3D=3D1. But what if each next iteration spawns more than two looping states? E.g. for the following example: 0. // full test attached as a patch 1. while (next(i)) { 2. if (random()) 3. continue; 4. if (random()) 5. continue; 6. if (random()) 7. continue; 8. r0 +=3D 0; 9. } For me it bails out with the following message: run_subtest:FAIL:unexpected_load_failure unexpected error: -28 .... The sequence of 8193 jumps is too complex. processed 49161 insns (limit 1000000) max_states_per_insn 4 total_state= s 2735 peak_states 2735 mark_read 2 (I bumped insn complexity limit back to 1,000,000). > With this patch all existing iter tests still pass, > and all Ed's special tests pass or fail as needed. > Ex: loop_state_deps1 is rejected with misaligned stack, > loop1 loads with success, num_iter_bug fails with bad pointer. Are you sure that correct version of the patch was shared? I get the following log for loop_state_deps1: run_subtest:FAIL:unexpected_load_success unexpected success: 0 from 21 to 22: safe ... update_br2 80c0 branches=3D0/0 processed 75 insns (limit 1000000) max_states_per_insn 2 total_states 2= 9 peak_states 29 mark_read 9 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D #104/26 iters/loop_state_deps1:FAIL The test case is marked as safe. iter_precision_fixed_point{1,2} and num_iter_bug work as expected. --=-I7sf5AKhnRvgCYTyaHin Content-Disposition: attachment; filename="hydra1.patch" Content-Type: text/x-patch; name="hydra1.patch"; charset="UTF-8" Content-Transfer-Encoding: base64 ZGlmZiAtLWdpdCBhL2tlcm5lbC9icGYvdmVyaWZpZXIuYyBiL2tlcm5lbC9icGYvdmVyaWZpZXIu YwppbmRleCAwMTljOGRkZTVmYTIuLmNmOTA0MWZhYzI3MiAxMDA2NDQKLS0tIGEva2VybmVsL2Jw Zi92ZXJpZmllci5jCisrKyBiL2tlcm5lbC9icGYvdmVyaWZpZXIuYwpAQCAtMTY4MjEsNyArMTY4 MjEsNyBAQCBzdGF0aWMgaW50IGRvX2NoZWNrKHN0cnVjdCBicGZfdmVyaWZpZXJfZW52ICplbnYp CiAJCWluc24gPSAmaW5zbnNbZW52LT5pbnNuX2lkeF07CiAJCWNsYXNzID0gQlBGX0NMQVNTKGlu c24tPmNvZGUpOwogCi0JCWlmICgrK2Vudi0+aW5zbl9wcm9jZXNzZWQgPiAxMDAwKSB7Ly9CUEZf Q09NUExFWElUWV9MSU1JVF9JTlNOUykgeworCQlpZiAoKytlbnYtPmluc25fcHJvY2Vzc2VkID4g QlBGX0NPTVBMRVhJVFlfTElNSVRfSU5TTlMpIHsKIAkJCXZlcmJvc2UoZW52LAogCQkJCSJCUEYg cHJvZ3JhbSBpcyB0b28gbGFyZ2UuIFByb2Nlc3NlZCAlZCBpbnNuXG4iLAogCQkJCWVudi0+aW5z bl9wcm9jZXNzZWQpOwpkaWZmIC0tZ2l0IGEvdG9vbHMvdGVzdGluZy9zZWxmdGVzdHMvYnBmL3By b2dzL2l0ZXJzLmMgYi90b29scy90ZXN0aW5nL3NlbGZ0ZXN0cy9icGYvcHJvZ3MvaXRlcnMuYwpp bmRleCA5YWRkNzFkNzlhM2EuLmYwODI4OGMwYjc0YSAxMDA2NDQKLS0tIGEvdG9vbHMvdGVzdGlu Zy9zZWxmdGVzdHMvYnBmL3Byb2dzL2l0ZXJzLmMKKysrIGIvdG9vbHMvdGVzdGluZy9zZWxmdGVz dHMvYnBmL3Byb2dzL2l0ZXJzLmMKQEAgLTk5MSw0ICs5OTEsNDIgQEAgaW50IG51bV9pdGVyX2J1 Zyhjb25zdCB2b2lkICpjdHgpIHsKICAgICAgcmV0dXJuIDA7CiB9CiAKK1NFQygiP3Jhd190cCIp CitfX3N1Y2Nlc3MKK19fbmFrZWQgaW50IGh5ZHJhMSh2b2lkKQoreworCWFzbSB2b2xhdGlsZSAo CisJCSJyMSA9IHIxMDsiCisJCSJyMSArPSAtODsiCisJCSJyMiA9IDA7IgorCQkicjMgPSAxMDsi CisJCSJjYWxsICVbYnBmX2l0ZXJfbnVtX25ld107IgorCSJsb29wXyU9OiIKKwkJInIxID0gcjEw OyIKKwkJInIxICs9IC04OyIKKwkJImNhbGwgJVticGZfaXRlcl9udW1fbmV4dF07IgorCQkiaWYg cjAgPT0gMCBnb3RvIGxvb3BfZW5kXyU9OyIKKwkJImNhbGwgJVticGZfZ2V0X3ByYW5kb21fdTMy XTsiCisJCSJpZiByMCAhPSA0MiBnb3RvIGxvb3BfJT07IgorCQkiY2FsbCAlW2JwZl9nZXRfcHJh bmRvbV91MzJdOyIKKwkJImlmIHIwICE9IDQyIGdvdG8gbG9vcF8lPTsiCisJCSJjYWxsICVbYnBm X2dldF9wcmFuZG9tX3UzMl07IgorCQkiaWYgcjAgIT0gNDIgZ290byBsb29wXyU9OyIKKwkJInIw ICs9IDA7IgorCQkiZ290byBsb29wXyU9OyIKKwkibG9vcF9lbmRfJT06IgorCQkicjEgPSByMTA7 IgorCQkicjEgKz0gLTg7IgorCQkiY2FsbCAlW2JwZl9pdGVyX251bV9kZXN0cm95XTsiCisJCSJy MCA9IDA7IgorCQkiZXhpdDsiCisJCToKKwkJOiBfX2ltbShicGZfZ2V0X3ByYW5kb21fdTMyKSwK KwkJICBfX2ltbShicGZfaXRlcl9udW1fbmV3KSwKKwkJICBfX2ltbShicGZfaXRlcl9udW1fbmV4 dCksCisJCSAgX19pbW0oYnBmX2l0ZXJfbnVtX2Rlc3Ryb3kpCisJCTogX19jbG9iYmVyX2FsbAor CSk7Cit9CisKIGNoYXIgX2xpY2Vuc2VbXSBTRUMoImxpY2Vuc2UiKSA9ICJHUEwiOwo= --=-I7sf5AKhnRvgCYTyaHin--