Public bug reported:
This new upstream version consists only of a couple security fixes, and
should thus be merged into Impish.
Upstream changelog:
Changes between 1.1.1k and 1.1.1l [24 Aug 2021]
*) 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]
Debian changelog:
openssl (1.1.1l-1) unstable; urgency=medium
* New upstream version.
- CVE-2021-3711 (SM2 Decryption Buffer Overflow).
- CVE-2021-3712 (Read buffer overruns processing ASN.1 strings).
-- Sebastian Andrzej Siewior <sebast...@breakpoint.cc> Wed, 25 Aug
2021 00:19:05 +0200
** Affects: openssl (Ubuntu)
Importance: Undecided
Status: New
** Tags: rls-ii-incoming
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https://bugs.launchpad.net/bugs/1943109
Title:
Merge 1.1.1l-1 version from Debian
Status in openssl package in Ubuntu:
New
Bug description:
This new upstream version consists only of a couple security fixes,
and should thus be merged into Impish.
Upstream changelog:
Changes between 1.1.1k and 1.1.1l [24 Aug 2021]
*) 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]
Debian changelog:
openssl (1.1.1l-1) unstable; urgency=medium
* New upstream version.
- CVE-2021-3711 (SM2 Decryption Buffer Overflow).
- CVE-2021-3712 (Read buffer overruns processing ASN.1 strings).
-- Sebastian Andrzej Siewior <sebast...@breakpoint.cc> Wed, 25 Aug
2021 00:19:05 +0200
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