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authorAndrzej Kurek <andrzej.kurek@arm.com>2020-04-14 09:49:52 -0400
committerAndrzej Kurek <andrzej.kurek@arm.com>2020-04-15 06:15:45 -0400
commit1605074f9796cb4d0c05b48485c9c7aeb08f4441 (patch)
tree800c5d0bd6980f559a411c759af7b318f26d11d5
parent8ea6872889f073876ca3b7c17a51eca419e06f50 (diff)
downloadmbed-tls-1605074f9796cb4d0c05b48485c9c7aeb08f4441.tar.gz
Guard from undefined behaviour in case of an INT_MAX max_pathlen
When parsing a certificate with the basic constraints extension the max_pathlen that was read from it was incremented regardless of its value. However, if the max_pathlen is equal to INT_MAX (which is highly unlikely), an undefined behaviour would occur. This commit adds a check to ensure that such value is not accepted as valid. Relevant tests for INT_MAX and INT_MAX-1 are also introduced. Certificates added in this commit were generated using the test_suite_x509write, function test_x509_crt_check. Input data taken from the "Certificate write check Server1 SHA1" test case, so the generated files are like the "server1.crt", but with the "is_ca" field set to 1 and max_pathlen as described by the file name. Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
-rw-r--r--library/x509_crt.c6
-rw-r--r--tests/data_files/server1_pathlen_int_max-1.crt20
-rw-r--r--tests/data_files/server1_pathlen_int_max.crt20
-rw-r--r--tests/suites/test_suite_x509parse.data8
4 files changed, 54 insertions, 0 deletions
diff --git a/library/x509_crt.c b/library/x509_crt.c
index 1e472303b..1e62ed5b0 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -524,6 +524,12 @@ static int x509_get_basic_constraints( unsigned char **p,
return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+ /* Do not accept max_pathlen equal to INT_MAX to avoid a signed integer
+ * overflow, which is an undefined behavior. */
+ if( *max_pathlen == INT_MAX )
+ return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
+ MBEDTLS_ERR_ASN1_INVALID_LENGTH );
+
(*max_pathlen)++;
return( 0 );
diff --git a/tests/data_files/server1_pathlen_int_max-1.crt b/tests/data_files/server1_pathlen_int_max-1.crt
new file mode 100644
index 000000000..4944844d7
--- /dev/null
+++ b/tests/data_files/server1_pathlen_int_max-1.crt
@@ -0,0 +1,20 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/tests/data_files/server1_pathlen_int_max.crt b/tests/data_files/server1_pathlen_int_max.crt
new file mode 100644
index 000000000..517e0d678
--- /dev/null
+++ b/tests/data_files/server1_pathlen_int_max.crt
@@ -0,0 +1,20 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/tests/suites/test_suite_x509parse.data b/tests/suites/test_suite_x509parse.data
index 3099e632d..7012e8e36 100644
--- a/tests/suites/test_suite_x509parse.data
+++ b/tests/suites/test_suite_x509parse.data
@@ -1798,6 +1798,14 @@ X509 CRT ASN1 (TBS, inv extBasicConstraint, no pathlen length)
depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA256_C
x509parse_crt:"3081b030819aa0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092A864886F70D010101050003190030160210ffffffffffffffffffffffffffffffff0202ffffa100a200a314301230100603551d130101010406300402010102300d06092a864886f70d01010b0500030200ff":"":MBEDTLS_ERR_X509_INVALID_EXTENSIONS + MBEDTLS_ERR_ASN1_OUT_OF_DATA
+X509 CRT ASN1 (inv extBasicConstraint, pathlen is INT_MAX)
+depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA256_C:MBEDTLS_SHA1_C
+x509parse_crt_file:"data_files/server1_pathlen_int_max.crt":MBEDTLS_ERR_X509_INVALID_EXTENSIONS + MBEDTLS_ERR_ASN1_INVALID_LENGTH
+
+X509 CRT ASN1 (pathlen is INT_MAX-1)
+depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA256_C:MBEDTLS_SHA1_C
+x509parse_crt_file:"data_files/server1_pathlen_int_max-1.crt":0
+
X509 CRT ASN1 (TBS, inv extBasicConstraint, pathlen inv length encoding)
depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA256_C
x509parse_crt:"3081b130819ba0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092A864886F70D010101050003190030160210ffffffffffffffffffffffffffffffff0202ffffa100a200a315301330110603551d13010101040730050201010285300d06092a864886f70d01010b0500030200ff":"":MBEDTLS_ERR_X509_INVALID_EXTENSIONS + MBEDTLS_ERR_ASN1_INVALID_LENGTH