pki_mbedtls: Simplify memory cleanup

Jakub Jelenrequested to merge
jjelen/libssh-mirror:mbedtls-blob into master

The spread out initialization and variable definition (and alising) was hell to keep up with and was causing memory issues as reported by valgrind:

==4480== 128 bytes in 1 blocks are definitely lost in loss record 1 of 12
==4480==    at 0x48463F3: calloc (vg_replace_malloc.c:1675)
==4480==    by 0x487D152: mbedtls_mpi_grow (bignum.c:218)
==4480==    by 0x487D6C5: mbedtls_mpi_copy (bignum.c:334)
==4480==    by 0x48B9627: mbedtls_rsa_export (rsa.c:899)
==4480==    by 0x283955: pki_key_to_blob (pki_mbedcrypto.c:976)
==4480==    by 0x24F162: ssh_pki_export_privkey_blob (pki.c:2188)
==4480==    by 0x278001: ssh_pki_openssh_privkey_export (pki_container_openssh.c:546)
==4480==    by 0x24D7D2: ssh_pki_export_privkey_file_format (pki.c:1122)
==4480==    by 0x24D916: torture_pki_rsa_write_privkey_format (torture_pki_rsa.c:895)
==4480==    by 0x24D916: torture_pki_rsa_write_privkey (torture_pki_rsa.c:962)
==4480==    by 0x4865499: ??? (in /usr/lib64/libcmocka.so.0.8.0)
==4480==    by 0x4865C0B: _cmocka_run_group_tests (in /usr/lib64/libcmocka.so.0.8.0)
==4480==    by 0x252115: torture_run_tests (torture_pki_rsa.c:1160)
==4480==    by 0x2546B8: main (torture.c:1984)
==4480==

Checklist

  • Commits have Signed-off-by: with name/author being identical to the commit author
  • Code modified for feature
  • Test suite updated with functionality tests
  • Test suite updated with negative tests
  • Documentation updated

Reviewer's checklist:

  • Any issues marked for closing are addressed
  • There is a test suite reasonably covering new functionality or modifications
  • Function naming, parameters, return values, types, etc., are consistent and according to CONTRIBUTING.md
  • This feature/change has adequate documentation added
  • No obvious mistakes in the code

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