use mbedtls_ssl_session_init() to init session variable

[BensonLiou]

Description

Use mbedtls_ssl_session_init() to init variable just like session-family APIs described

PR checklist

Please tick as appropriate and edit the reasons (e.g.: "backport: not needed because this is a new feature")

• [x] changelog not required
• [ ] backport required
• [x] tests not required

Notes for the submitter

Please refer to the contributing guidelines, especially the checklist for PR contributors.

[yanesca]

@BensonLiou Thank you for your contribution. Could you please raise a PR with a backport? (Same commit on the top of the mbedtls-2.28 branch.)

[BensonLiou]

Hi, I didn't find a page to describe how to do backport correctly. I assume the steps should be

1. checkout to mbedtls-2.28 and create a branch
2. CP the commit
3. push Please let me know if it's right or not Thanks

[gilles-peskine-arm]

checkout to mbedtls-2.28 and create a branch CP the commit push

Yes, that's right. (For completeness: if there are many commits, you might prefer (starting from mybranch) git checkout -b mybranch-2.28 && git rebase --onto origin/mbedtls-2.28 origin/development mybranch-2.28 which is equivalent to cherry-picking the commits one by one.)

[BensonLiou]

Hi @gilles-peskine-arm Thanks for the information. The backport PR is https://github.com/Mbed-TLS/mbedtls/pull/8841