I have this bug too, same hardware. A bit of inexpert investigation: OsLookupColor is defined in xserver/os/oscolor.c: https://gitlab.freedesktop.org/xorg/xserver/blob/master/os/oscolor.c#L1633
I don't know what version numbers this change involves, but that file hasn't changed since 2017 and the xserver/include/os.h file that declares that function hasn't changed since May 2019, so it seems unlikely to be the direct culprit. It does basically zero validation of its inputs though, so even if there's no off-by-one errors in its slightly-suspicious binary search it's probably getting passed bad inputs, either a nonsense string or bad output pointers. Will try to get a full stack trace and figure out what it's doing and where it's coming from. Regards, Simon
