On Tue, Apr 27, 2010 at 07:05:44PM +0200, Jim Meyering wrote:
Some people have expressed an interest in setting up a libvirt autobuilder using clang. If you do that, be aware that you'll see an ugly looking NULL-deref problem when using the clang that comes with F12 or F13, but if you're using a new enough version (rawhide), it's gone. The offending code is in qemu_monitor.c around line 377 and involves the CMSG_* macros:
365 memset(&msg, 0, sizeof(msg)); 366 367 iov[0].iov_base = (void *)data; 368 iov[0].iov_len = len; 369 370 msg.msg_iov = iov; 371 msg.msg_iovlen = 1; 372 373 msg.msg_control = control; 374 msg.msg_controllen = sizeof(control); 375 376 cmsg = CMSG_FIRSTHDR(&msg)((size_t) (&msg)->msg_controllen >= sizeof (struct cmsghdr ) ? (struct cmsghdr *) (&msg)->msg_control : (struct cmsghdr *) 0);
*** 2 Null pointer value stored to 'cmsg'
377 cmsg->cmsg_len = CMSG_LEN(sizeof(int))((((sizeof (struct cmsghdr)) + sizeof (size_t) - 1) & (size_t) ~(sizeof (size_t) - 1)) + (sizeof(int)));
*** 3 Dereference of null pointer
Presuming this code is actually exercised, it's obviously not dereferencing NULL, so it would be a false positive. I looked at a few usage examples and it seems like glibc's own tests do allocate more storage. If this code is *not* currently being used, we should model it after the glibc test code.
Yes, this code is used for network interface hotplug & works correctly in our testing. Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://deltacloud.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|