Changes between 1.1.1k and 1.1.1l [xx XXX xxxx]
- *)
+ *) Fixed an SM2 Decryption Buffer Overflow.
+
+ In order to decrypt SM2 encrypted data an application is expected to call the
+ API function EVP_PKEY_decrypt(). Typically an application will call this
+ function twice. The first time, on entry, the "out" parameter can be NULL and,
+ on exit, the "outlen" parameter is populated with the buffer size required to
+ hold the decrypted plaintext. The application can then allocate a sufficiently
+ sized buffer and call EVP_PKEY_decrypt() again, but this time passing a non-NULL
+ value for the "out" parameter.
+
+ A bug in the implementation of the SM2 decryption code means that the
+ calculation of the buffer size required to hold the plaintext returned by the
+ first call to EVP_PKEY_decrypt() can be smaller than the actual size required by
+ the second call. This can lead to a buffer overflow when EVP_PKEY_decrypt() is
+ called by the application a second time with a buffer that is too small.
+
+ A malicious attacker who is able present SM2 content for decryption to an
+ application could cause attacker chosen data to overflow the buffer by up to a
+ maximum of 62 bytes altering the contents of other data held after the
+ buffer, possibly changing application behaviour or causing the application to
+ crash. The location of the buffer is application dependent but is typically
+ heap allocated.
+ (CVE-2021-3711)
+ [Matt Caswell]
+
+ *) Fixed various read buffer overruns processing ASN.1 strings
+
+ ASN.1 strings are represented internally within OpenSSL as an ASN1_STRING
+ structure which contains a buffer holding the string data and a field holding
+ the buffer length. This contrasts with normal C strings which are repesented as
+ a buffer for the string data which is terminated with a NUL (0) byte.
+
+ Although not a strict requirement, ASN.1 strings that are parsed using OpenSSL's
+ own "d2i" functions (and other similar parsing functions) as well as any string
+ whose value has been set with the ASN1_STRING_set() function will additionally
+ NUL terminate the byte array in the ASN1_STRING structure.
+
+ However, it is possible for applications to directly construct valid ASN1_STRING
+ structures which do not NUL terminate the byte array by directly setting the
+ "data" and "length" fields in the ASN1_STRING array. This can also happen by
+ using the ASN1_STRING_set0() function.
+
+ Numerous OpenSSL functions that print ASN.1 data have been found to assume that
+ the ASN1_STRING byte array will be NUL terminated, even though this is not
+ guaranteed for strings that have been directly constructed. Where an application
+ requests an ASN.1 structure to be printed, and where that ASN.1 structure
+ contains ASN1_STRINGs that have been directly constructed by the application
+ without NUL terminating the "data" field, then a read buffer overrun can occur.
+
+ The same thing can also occur during name constraints processing of certificates
+ (for example if a certificate has been directly constructed by the application
+ instead of loading it via the OpenSSL parsing functions, and the certificate
+ contains non NUL terminated ASN1_STRING structures). It can also occur in the
+ X509_get1_email(), X509_REQ_get1_email() and X509_get1_ocsp() functions.
+
+ If a malicious actor can cause an application to directly construct an
+ ASN1_STRING and then process it through one of the affected OpenSSL functions
+ then this issue could be hit. This might result in a crash (causing a Denial of
+ Service attack). It could also result in the disclosure of private memory
+ contents (such as private keys, or sensitive plaintext).
+ (CVE-2021-3712)
+ [Matt Caswell]
Changes between 1.1.1j and 1.1.1k [25 Mar 2021]
projects / openssl.git / commitdiff