I remember that PR for similarly interesting reasons:
Someone on the pgsql-hackers@ mailing list noticed that, with a then-recent OpenSSL version on graviton, there were issues validating the "control file" of a PostgreSQL instance [0] (control files contain some basic ground truths about a cluster).
The report included a lot of detailed information about the program state, sufficient for me to figure out that one of the registers was definitely getting clobbered during the pg_strong_random() calls[1], but without access to the environment I couldn't prove whether it was the OpenSSL library, or a compiler bug.
A few days later an Apt developer was debugging the same issue from another direction, eventually figured out that this was caused by a typo in openssl's register restoration code (which was written in ASM introduced in the PR linked by parent post), and then submitted a PR to OpenSSL to fix the issue [2], now (presumably) for good.
Someone on the pgsql-hackers@ mailing list noticed that, with a then-recent OpenSSL version on graviton, there were issues validating the "control file" of a PostgreSQL instance [0] (control files contain some basic ground truths about a cluster).
The report included a lot of detailed information about the program state, sufficient for me to figure out that one of the registers was definitely getting clobbered during the pg_strong_random() calls[1], but without access to the environment I couldn't prove whether it was the OpenSSL library, or a compiler bug.
A few days later an Apt developer was debugging the same issue from another direction, eventually figured out that this was caused by a typo in openssl's register restoration code (which was written in ASM introduced in the PR linked by parent post), and then submitted a PR to OpenSSL to fix the issue [2], now (presumably) for good.
[0] https://postgr.es/m/Z4VjonBTm6IG8mGa%40msg.df7cb.de
[1] https://postgr.es/m/CAEze2WiRijBaoeFgi1JvsZeO6qXvpYkh4ax1bUV...
[2] https://github.com/openssl/openssl/pull/26469