On Wed, Oct 27, 2021 at 10:10:35PM +0200, Lennart Poettering wrote: > On Mi, 27.10.21 20:34, Richard W.M. Jones (rjones@xxxxxxxxxx) wrote: > > > I have a habit of setting: > > > > export GLIBC_TUNABLES=glibc.malloc.check=1:glibc.malloc.perturb=99 > > > > which causes glibc to do extra malloc integrity checks. In Rawhide at > > the moment I'm seeing memory corruption in calls like getpwnam and > > gethostbyname. Unfortunately I don't have a simple reproducer yet, > > but two example stack traces are below. I have the latest glibc and > > systemd. > > > > Questions: Has anyone seen this before, and what component should I > > file the bug against? > > > > Rich. > > > > Core was generated by `tar -C /var/tmp/supermin36875b.tmpdir/base.d -xf -'. > > Program terminated with signal SIGSEGV, Segmentation fault. > > #0 malloc_check_get_size (mem=0x0) > > at /usr/src/debug/glibc-2.34.9000-15.fc36.x86_64/malloc/malloc-check.c:39 > > 39 magic = (((uintptr_t) p >> 3) ^ ((uintptr_t) p >> 11)) & 0xFF; > > (gdb) bt > > #0 malloc_check_get_size (mem=0x0) > > at /usr/src/debug/glibc-2.34.9000-15.fc36.x86_64/malloc/malloc-check.c:39 > > #1 malloc_usable_size (mem=0x0) at malloc-debug.c:405 > > #2 0x00007f0eed847f1a in varlink_read (v=0x55c537e3e1c0) > > at ../src/shared/varlink.c:508 > > This is nss-systemd code, i.e. this is triggered by systemd code. > > It seems those "extra malloc integrity checks" can't cope with > malloc_usable_size(NULL) being called. According to the man page it's > a supported call (and returns 0), but I figue the e. m. i. c. don't > handle this. > > Hence smells to me as if this was a bug in glibc, to handle the > special case of NULL here. Fair enough, thanks Lennart, Zbigniew. I have filed a bug against glibc: https://sourceware.org/bugzilla/show_bug.cgi?id=28506 Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
