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Wed, 13 Aug 2025 11:14:28 -0700 (PDT) MIME-Version: 1.0 References: <20250813133812.926145-1-ethan.w.s.graham@gmail.com> <20250813133812.926145-7-ethan.w.s.graham@gmail.com> In-Reply-To: <20250813133812.926145-7-ethan.w.s.graham@gmail.com> From: Marco Elver Date: Wed, 13 Aug 2025 20:13:51 +0200 X-Gm-Features: Ac12FXwt2pSL7dVwRutKcMu_hFjjWXkjb4Jh6zDHbgaT8hltdL3d-RuGkNjKm24 Message-ID: Subject: Re: [PATCH v1 RFC 6/6] crypto: implement KFuzzTest targets for PKCS7 and RSA parsing To: Ethan Graham Cc: ethangraham@google.com, glider@google.com, andreyknvl@gmail.com, brendan.higgins@linux.dev, davidgow@google.com, dvyukov@google.com, jannh@google.com, rmoar@google.com, shuah@kernel.org, tarasmadan@google.com, kasan-dev@googlegroups.com, kunit-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, David Howells , Lukas Wunner , Ignat Korchagin , Herbert Xu , "David S. Miller" , "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: mdn3986ksya8m71ogxod8ewfpf1ofzt8 X-Rspam-User: X-Rspamd-Queue-Id: C60AA100009 X-Rspamd-Server: rspam05 X-HE-Tag: 1755108869-817260 X-HE-Meta: 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 ceWkIEX8 rPM+AiFfiwIQnGVgH6ei5KVVhnsTz+fTWg9GdYso9VC/tJmaWw+thcZN03gTlL1ZpvVZ+dsJUhrys87sJoNxkHibLuBxOCC6egJOBDCTi7CK9Mr9cJzjRQf5+WzKoG23jnvhydqyUE8dGpyjNab2idQP3lsW7vMHraHTJfl7EntcffLFufYnoMW+yYZg/F0i8iaycxdmmfEygWeTwcvZApccM8/zbaX8xeJb1iCdrjzNAVdTlP8vmutKbvvD91z20RbAIYbn8P0QdsDRv3+TC5ACIUzl3KmySybLFJv/yWtQu0AuFQ7+DdBZUVc+0qaIiCTlLgAWg4H/l1ZgWAd6G6aMDavFmF/zor3bV 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: [+Cc crypto maintainers] On Wed, 13 Aug 2025 at 15:38, Ethan Graham wrote: > > From: Ethan Graham Should also Cc crypto maintainers, as they'll be the ones giving feedback on how interesting this is to them. Use ./scripts/get_maintainer.pl for that in the next round, and either add the Cc list below your Signed-off-by so that git send-email picks it up only for this patch, or just for the whole series (normally preferred, so maintainers get context of the full series). > Add KFuzzTest targets for pkcs7_parse_message, rsa_parse_pub_key, and > rsa_parse_priv_key to serve as real-world examples of how the framework is used. > > These functions are ideal candidates for KFuzzTest as they perform complex > parsing of user-controlled data but are not directly exposed at the syscall > boundary. This makes them difficult to exercise with traditional fuzzing tools > and showcases the primary strength of the KFuzzTest framework: providing an > interface to fuzz internal, non-exported kernel functions. > > The targets are defined directly within the source files of the functions they > test, demonstrating how to colocate fuzz tests with the code under test. > > Signed-off-by: Ethan Graham > --- > crypto/asymmetric_keys/pkcs7_parser.c | 15 ++++++++++++++ > crypto/rsa_helper.c | 29 +++++++++++++++++++++++++++ > 2 files changed, 44 insertions(+) > > diff --git a/crypto/asymmetric_keys/pkcs7_parser.c b/crypto/asymmetric_keys/pkcs7_parser.c > index 423d13c47545..e8477f8b0eaf 100644 > --- a/crypto/asymmetric_keys/pkcs7_parser.c > +++ b/crypto/asymmetric_keys/pkcs7_parser.c > @@ -13,6 +13,7 @@ > #include > #include > #include > +#include > #include "pkcs7_parser.h" > #include "pkcs7.asn1.h" > > @@ -169,6 +170,20 @@ struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen) > } > EXPORT_SYMBOL_GPL(pkcs7_parse_message); > > +struct pkcs7_parse_message_arg { > + const void *data; > + size_t datalen; > +}; > + > +FUZZ_TEST(test_pkcs7_parse_message, struct pkcs7_parse_message_arg) > +{ > + KFUZZTEST_EXPECT_NOT_NULL(pkcs7_parse_message_arg, data); > + KFUZZTEST_ANNOTATE_LEN(pkcs7_parse_message_arg, datalen, data); > + KFUZZTEST_EXPECT_LE(pkcs7_parse_message_arg, datalen, 16 * PAGE_SIZE); > + > + pkcs7_parse_message(arg->data, arg->datalen); > +} > + > /** > * pkcs7_get_content_data - Get access to the PKCS#7 content > * @pkcs7: The preparsed PKCS#7 message to access > diff --git a/crypto/rsa_helper.c b/crypto/rsa_helper.c > index 94266f29049c..79b7ddc7c48d 100644 > --- a/crypto/rsa_helper.c > +++ b/crypto/rsa_helper.c > @@ -9,6 +9,7 @@ > #include > #include > #include > +#include > #include > #include "rsapubkey.asn1.h" > #include "rsaprivkey.asn1.h" > @@ -166,6 +167,20 @@ int rsa_parse_pub_key(struct rsa_key *rsa_key, const void *key, > } > EXPORT_SYMBOL_GPL(rsa_parse_pub_key); > > +struct rsa_parse_pub_key_arg { > + const void *key; > + size_t key_len; > +}; > + > +FUZZ_TEST(test_rsa_parse_pub_key, struct rsa_parse_pub_key_arg) > +{ > + KFUZZTEST_EXPECT_NOT_NULL(rsa_parse_pub_key_arg, key); > + KFUZZTEST_EXPECT_LE(rsa_parse_pub_key_arg, key_len, 16 * PAGE_SIZE); > + > + struct rsa_key out; > + rsa_parse_pub_key(&out, arg->key, arg->key_len); > +} > + > /** > * rsa_parse_priv_key() - decodes the BER encoded buffer and stores in the > * provided struct rsa_key, pointers to the raw key > @@ -184,3 +199,17 @@ int rsa_parse_priv_key(struct rsa_key *rsa_key, const void *key, > return asn1_ber_decoder(&rsaprivkey_decoder, rsa_key, key, key_len); > } > EXPORT_SYMBOL_GPL(rsa_parse_priv_key); > + > +struct rsa_parse_priv_key_arg { > + const void *key; > + size_t key_len; > +}; > + > +FUZZ_TEST(test_rsa_parse_priv_key, struct rsa_parse_priv_key_arg) > +{ > + KFUZZTEST_EXPECT_NOT_NULL(rsa_parse_priv_key_arg, key); > + KFUZZTEST_EXPECT_LE(rsa_parse_priv_key_arg, key_len, 16 * PAGE_SIZE); > + > + struct rsa_key out; > + rsa_parse_priv_key(&out, arg->key, arg->key_len); > +} > -- > 2.51.0.rc0.205.g4a044479a3-goog >