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[34.76.220.87]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b8f8b1bc81sm25677444f8f.69.2025.08.13.06.38.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Aug 2025 06:38:43 -0700 (PDT) From: Ethan Graham To: ethangraham@google.com, glider@google.com Cc: andreyknvl@gmail.com, brendan.higgins@linux.dev, davidgow@google.com, dvyukov@google.com, jannh@google.com, elver@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 Subject: [PATCH v1 RFC 6/6] crypto: implement KFuzzTest targets for PKCS7 and RSA parsing Date: Wed, 13 Aug 2025 13:38:12 +0000 Message-ID: <20250813133812.926145-7-ethan.w.s.graham@gmail.com> X-Mailer: git-send-email 2.51.0.rc0.205.g4a044479a3-goog In-Reply-To: <20250813133812.926145-1-ethan.w.s.graham@gmail.com> References: <20250813133812.926145-1-ethan.w.s.graham@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Ethan Graham 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 to= ols 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 t= hey 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" =20 @@ -169,6 +170,20 @@ struct pkcs7_message *pkcs7_parse_message(const void *= data, size_t datalen) } EXPORT_SYMBOL_GPL(pkcs7_parse_message); =20 +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 v= oid *key, } EXPORT_SYMBOL_GPL(rsa_parse_pub_key); =20 +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); +} --=20 2.51.0.rc0.205.g4a044479a3-goog