Mbedtls 2.19.1 fails to build from source with MBEDTLS_ZLIB_SUPPORT

[jack-fortanix]

Description

• Type: Bug

Bug

OS : any

mbed TLS build: 2.19.1
Configuration: MBEDTLS_ZLIB_SUPPORT
Compiler and options: gcc/any

Steps to reproduce
Uncomment MBEDTLS_ZLIB_SUPPORT from the default config.h and attempt to build:

[ 19%] Building C object library/CMakeFiles/mbedtls.dir/ssl_tls.c.o
/home/jack/sw/mbedtls/library/ssl_tls.c: In function ‘mbedtls_ssl_derive_keys’:
/home/jack/sw/mbedtls/library/ssl_tls.c:1862:9: error: ‘session’ undeclared (first use in this function); did you mean ‘setsid’?
     if( session->compression == MBEDTLS_SSL_COMPRESS_DEFLATE &&
         ^~~~~~~
         setsid

Looks to have been introduced between 2.18.0 and 2.19.0 though I could not find the exact commit. I believe this should now be ssl->session_negotiate->compression

[RonEld]

Hi @jack-fortanix Thank you for your input!
As you can see from the ChangeLog ZLIB support has been deprecated. So you should have received a build error, but it should have been a deprecation error, and probably not this error.

I would actually rename this bug to: "Deprecated ferature MBEDTLS_ZLIB_SUPPORT still used in some locations", or something better in grammar

[gilles-peskine-arm]

@RonEld I don't think that's the issue: MBEDTLS_ZLIB_SUPPORT is deprecated, but the feature is still supported for now, so if you enable it, it should work.

We have a test gap: we never test MBEDTLS_ZLIB_SUPPORT in all.sh.