kwallet sets a limit of 1000 for a single characters for environment
variables read from the socket[1]. wrapQtApps gives us a huge value
for QT_PLUGIN_PATH (up to 13000 bytes on my system!) Since this was
overflowing, the Qt plugin loading mechanism was hitting a segfault
when it was trying to parse the truncated QT_PLUGIN_PATH.
So for now, we can just unset QT_PLUGIN_PATH in the pam_kwallet_init
script. kwalletd5 has its own QT_PLUGIN_PATH which it can use.
This problem occured on 20.03, but not 19.09. It’s unclear what
changes were made in that time, but likely that previously we weren’t
getting a QT_PLUGIN_PATH set in the plasma5 startup at all. This means
that in 19.09 our QT_PLUGIN_PATH value must have been small enough to
fit into the 1000 char limit.
Fixes#77290
[1]: bc9713e272/src/runtime/kwalletd/main.cpp (L44)
/cc @ttuegel
f0db4de598