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AJvYcCVkSp2aLNbndfec2ypEx3pDnK09XGRWCsFpxZbtaBr72lUpqK2rbNuh2E9GyHeIxAYrNsu51RKIOQ==@kvack.org X-Gm-Message-State: AOJu0YyyZF52DDfBQvHZ9mqdIaF8bVawSLP968doVUGUov/aFL4T65it 8fUqHt2+sGzggG7I16Xr+tHFxUvSdSjLUwxzkE91OIGrAOrXFEThV6mG053c++7Mc/nlRkSyeon vh3G7x8sTWJVseH8nYMyLzAP1tpkETVGFsxiq6+EP X-Gm-Gg: ASbGncuEhMXdQ8MjKUh6C049IGdPI6HYC1weIYmbcCUXUxex8ekOuVgBzBKNuycDIRE ufIfuztiXc1aCaWbGHRDuppIjQdTijiJqeMNhxUPp78e9nyPsGzkTer7782VyR25JA9xxlO74By CYm8sLN7x94H8s53aJcNq2v/0dF6AlptkT9vFEKdHbvRDVc2BqqguWNwCZ3Inlr9y98yUlWMEdE 0x5hSfq2w2Lrk3Fq4Z97KDNixILFKP/g3BWHA== X-Google-Smtp-Source: AGHT+IGrLhGnLin4JPn3IEJL16TDaAaIyPUzt4DPnDcGALtByT5b0deWvFSW43f3QYgleVc8ho2F2zEcC/AGvOdoPJI= X-Received: by 2002:a05:6214:5712:b0:7b0:d5a0:c60d with SMTP id 6a1803df08f44-7b0d5a0c6c5mr11507116d6.10.1758370120098; Sat, 20 Sep 2025 05:08:40 -0700 (PDT) MIME-Version: 1.0 References: <20250919145750.3448393-1-ethan.w.s.graham@gmail.com> <20250919145750.3448393-9-ethan.w.s.graham@gmail.com> In-Reply-To: From: Alexander Potapenko Date: Sat, 20 Sep 2025 14:08:01 +0200 X-Gm-Features: AS18NWBVqpbu6_S8igqrpC6d_4rlaGzIrca9Y3paJY9H7AfaiH53k8LL1oZq4JA Message-ID: Subject: Re: [PATCH v2 08/10] drivers/auxdisplay: add a KFuzzTest for parse_xy() To: Andy Shevchenko Cc: Ethan Graham , ethangraham@google.com, andreyknvl@gmail.com, andy@kernel.org, brauner@kernel.org, brendan.higgins@linux.dev, davem@davemloft.net, davidgow@google.com, dhowells@redhat.com, dvyukov@google.com, elver@google.com, herbert@gondor.apana.org.au, ignat@cloudflare.com, jack@suse.cz, jannh@google.com, johannes@sipsolutions.net, kasan-dev@googlegroups.com, kees@kernel.org, kunit-dev@googlegroups.com, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lukas@wunner.de, rmoar@google.com, shuah@kernel.org, sj@kernel.org, tarasmadan@google.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 44592180018 X-Stat-Signature: ts5mh6sgsi79x6otcxrhmoyx3h8jpqc1 X-Rspam-User: X-HE-Tag: 1758370121-154234 X-HE-Meta: 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 FEvpcrd1 56l5vZyylfI++aZs9qFLbK+IujgdcCwgSjs8aWRQr0+IUEVfvuuc5hWMG36nAO8qcq2p/PLKkzLCMjKLGWxvQhvLIj95Wwq2/YNOxqF2KF6DItZ4II1iTyROum4F5VNbjIP+afbi7jMgs9/lngxaEqFZyv0sF0m+ORSgT5H4682pPpRDp6fksuWZlVFv4nVjEkiH3ziZ8YyOjKJmH+F5aklMpbxptRaMlO5zNUCGsJTkhc76XWG0lusY9MCkC46dxLdhx3BP3P58XGx/ajh2D+hTtihwM5qgZgaYV+Xq9gystMFio+xMYc3zcEbv/XDrUMjPr++kbYfrr7ngh2yJPsiIhFV02lNB55eIAwFezGgHP7aY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, Sep 20, 2025 at 12:54=E2=80=AFPM Andy Shevchenko wrote: > > On Fri, Sep 19, 2025 at 5:58=E2=80=AFPM Ethan Graham wrote: > > > > From: Ethan Graham > > > > Add a KFuzzTest fuzzer for the parse_xy() function, located in a new > > file under /drivers/auxdisplay/tests. > > > > To validate the correctness and effectiveness of this KFuzzTest target, > > a bug was injected into parse_xy() like so: > > > > drivers/auxdisplay/charlcd.c:179 > > - s =3D p; > > + s =3D p + 1; > > > > Although a simple off-by-one bug, it requires a specific input sequence > > in order to trigger it, thus demonstrating the power of pairing > > KFuzzTest with a coverage-guided fuzzer like syzkaller. > > ... > > > --- a/drivers/auxdisplay/charlcd.c > > +++ b/drivers/auxdisplay/charlcd.c > > @@ -682,3 +682,11 @@ EXPORT_SYMBOL_GPL(charlcd_unregister); > > > > MODULE_DESCRIPTION("Character LCD core support"); > > MODULE_LICENSE("GPL"); > > + > > +/* > > + * When CONFIG_KFUZZTEST is enabled, we include this _kfuzz.c file to = ensure > > + * that KFuzzTest targets are built. > > + */ > > +#ifdef CONFIG_KFUZZTEST > > +#include "tests/charlcd_kfuzz.c" > > +#endif /* CONFIG_KFUZZTEST */ > > No, NAK. We don't want to see these in each and every module. Please, > make sure that nothing, except maybe Kconfig, is modified in this > folder (yet, you may add a _separate_ test module, as you already have > done in this patch). This is one of the cases in which we can't go without changing the original code, because parse_xy() is a static function. Including the test into the source is not the only option, we could as well make the function visible unconditionally, or introduce a macro similar to VISIBLE_IF_KUNIT. Do you prefer any of those?