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@paul-elliott-arm paul-elliott-arm released this 28 Mar 12:50
· 1237 commits to mbedtls-2.28 since this release
v2.28.3
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Description

This release of Mbed TLS provides bug fixes and minor enhancements. This release includes fixes for security issues.

Mbed TLS 2.28 is a long-time support branch. It will be supported with bug-fixes and security fixes until end of 2024.

Security Advisories

There are no security advisories for this release.

Release Notes

Features

  • Use HOSTCC (if it is set) when compiling C code during generation of the
    configuration-independent files. This allows them to be generated when
    CC is set for cross compilation.
  • AES-NI is now supported with Visual Studio.
  • AES-NI is now supported in 32-bit builds, or when MBEDTLS_HAVE_ASM
    is disabled, when compiling with GCC or Clang or a compatible compiler
    for a target CPU that supports the requisite instructions (for example
    gcc -m32 -msse2 -maes -mpclmul). (Generic x86 builds with GCC-like
    compilers still require MBEDTLS_HAVE_ASM and a 64-bit target.)

Security

  • MBEDTLS_AESNI_C, which is enabled by default, was silently ignored on
    builds that couldn't compile the GCC-style assembly implementation
    (most notably builds with Visual Studio), leaving them vulnerable to
    timing side-channel attacks. There is now an intrinsics-based AES-NI
    implementation as a fallback for when the assembly one cannot be used.

Bugfix

  • Fix a build issue on Windows where the source and build directory could
    not be on different drives (#5751).
  • Fix possible integer overflow in mbedtls_timing_hardclock(), which
    could cause a crash for certain platforms & compiler options.
  • Fix IAR compiler warnings. Fixes #6924.
  • Fix a bug in the build where directory names containing spaces were
    causing generate_errors.pl to error out resulting in a build failure.
    Fixes issue #6879.
  • Fix compile error where MBEDTLS_RSA_C and MBEDTLS_X509_CRT_WRITE_C are
    defined, but MBEDTLS_PK_RSA_ALT_SUPPORT is not defined. Fixes #3174.
  • Fix a build issue when defining MBEDTLS_TIMING_ALT and MBEDTLS_SELF_TEST.
    The library would not link if the user didn't provide an external self-test
    function. The self-test is now provided regardless of the choice of
    internal/alternative timing implementation. Fixes #6923.
  • mbedtls_x509write_crt_set_serial() now explicitly rejects serial numbers
    whose binary representation is longer than 20 bytes. This was already
    forbidden by the standard (RFC5280 - section 4.1.2.2) and now it's being
    enforced also at code level.
  • Fix potential undefined behavior in mbedtls_mpi_sub_abs(). Reported by
    Pascal Cuoq using TrustInSoft Analyzer in #6701; observed independently by
    Aaron Ucko under Valgrind.
  • Fix behavior of certain sample programs which could, when run with no
    arguments, access uninitialized memory in some cases. Fixes #6700 (which
    was found by TrustInSoft Analyzer during REDOCS'22) and #1120.
  • Fix build errors in test programs when MBEDTLS_CERTS_C is disabled.
    Fixes #6243.
  • Fix parsing of X.509 SubjectAlternativeName extension. Previously,
    malformed alternative name components were not caught during initial
    certificate parsing, but only on subsequent calls to
    mbedtls_x509_parse_subject_alt_name(). Fixes #2838.
  • Fix bug in conversion from OID to string in
    mbedtls_oid_get_numeric_string(). OIDs such as 2.40.0.25 are now printed
    correctly.
  • Reject OIDs with overlong-encoded subidentifiers when converting
    them to a string.
  • Reject OIDs with subidentifier values exceeding UINT_MAX. Such
    subidentifiers can be valid, but Mbed TLS cannot currently handle them.
  • Reject OIDs that have unterminated subidentifiers, or (equivalently)
    have the most-significant bit set in their last byte.
  • Silence a warning about an unused local variable in bignum.c on
    some architectures. Fixes #7166.
  • Silence warnings from clang -Wdocumentation about empty \retval
    descriptions, which started appearing with Clang 15. Fixes #6960.
  • Fix undefined behavior in mbedtls_ssl_read() and mbedtls_ssl_write() if
    len argument is 0 and buffer is NULL.

Changes

  • The C code follows a new coding style. This is transparent for users but
    affects contributors and maintainers of local patches. For more
    information, see
    https://mbed-tls.readthedocs.io/en/latest/kb/how-to/rewrite-branch-for-coding-style/
  • Changed the default MBEDTLS_ECP_WINDOW_SIZE from 6 to 2.
    As tested in issue 6790, the correlation between this define and
    RSA decryption performance has changed lately due to security fixes.
    To fix the performance degradation when using default values the
    window was reduced from 6 to 2, a value that gives the best or close
    to best results when tested on Cortex-M4 and Intel i7.

Who should update

We recommend all users should update to take advantage of the bug fixes contained in this release at an appropriate point in their development lifecycle.

Checksum

The SHA256 hashes for the archives are:

bdf7c5bbdc338da3edad89b2885d4f8668f9a6fffeba6ec17a60333e36dade6f mbedtls-2.28.3.tar.gz
0c0abbd6e33566c5c3c15af4fc19466c8edb62fa483d4ce98f1ba3f656656d2d mbedtls-2.28.3.zip

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