[openssl/openssl] 106794: bn: Properly error out if aliasing return value wi...

[Tomáš Mráz]

  Branch: refs/heads/openssl-3.1
  Home:   https://github.com/openssl/openssl
  Commit: 1067944c12691c7311c50d565e02cc53577b0f09
      https://github.com/openssl/openssl/commit/1067944c12691c7311c50d565e02cc53577b0f09
  Author: Tomas Mraz <tomas at openssl.org>
  Date:   2023-10-26 (Thu, 26 Oct 2023)

  Changed paths:
    M crypto/bn/bn_exp.c
    M crypto/bn/bn_mod.c
    M doc/man3/BN_add.pod
    M doc/man3/BN_mod_inverse.pod
    M test/bntest.c

  Log Message:
  -----------
  bn: Properly error out if aliasing return value with modulus

Test case amended from code initially written by Bernd Edlinger.

Fixes #21110

Reviewed-by: Dmitry Belyavskiy <beldmit at gmail.com>
Reviewed-by: Paul Dale <pauli at openssl.org>
Reviewed-by: Hugo Landau <hlandau at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22421)

(cherry picked from commit af0025fc40779cc98c06db7e29936f9d5de8cc9e)