Comment 10 for bug 1904419

Revision history for this message
bugproxy (bugproxy) wrote : Comment bridged from LTC Bugzilla

------- Comment From <email address hidden> 2020-12-11 10:43 EDT-------
It has nothing to do with a performance improvement. It's just broken. Thus your Ubuntu 20.10 has a regression compared to Ubuntu 20.04! The issues were reported via glibc-upstream bugzillas:
- "Bug 26636 - 32-bit shmctl(IPC_INFO) crashes when shminfo struct is at the end of a memory mapping ":
...
Compile attached test program:
gcc -m32 -o ~/tmp/test ~/tmp/test.c
It should print something like "max=2147483647". With the above glibc commit, it crashes.
...
This causes an rr test failure: https://github.com/mozilla/rr/issues/2681

- "Bug 26639 - msgctl IPC_INFO and MSG_INFO return garbage "
Starting with commit glibc-2.31.9000-687-g3283f71113 aka glibc-2.32~83,
both IPC_INFO and MSG_INFO commands of msgctl return garbage because their argument of type "struct msginfo" is converted using kmsqid64_to_msqid64.
This bug was found by strace test suite.

- "Bug 26637 - semctl SEM_STAT_ANY fails to pass the buffer specified by the caller to the kernel"
The kernel receives garbage instead of union semun.buf address specified by the caller.
...
(As Dimitry has reported this bug on the same day as Bug 26639, I assume he also found it by strace test suite.)

The glibc-commits have added new testcaes which are run with "make check" while building the libc6 package. I assume you are monitoring those testfails.