Author: markj Date: Tue Oct 8 23:34:48 2019 New Revision: 353331 URL: https://svnweb.freebsd.org/changeset/base/353331
Log: Fix handling of empty SCM_RIGHTS messages. As unp_internalize() processes the input control messages, it builds an output mbuf chain containing the internalized representations of those messages. In one special case, that of an empty SCM_RIGHTS message, the message is simply discarded. However, the loop which appends mbufs to the output chain assumed that each iteration would produce an mbuf, resulting in a null pointer dereference if an empty SCM_RIGHTS message was followed by a non-empty message. Fix this by advancing the output mbuf chain tail pointer only if an internalized control message was produced. Reported by: syzbot+1b5cced0f7fad26ae...@syzkaller.appspotmail.com MFC after: 1 week Sponsored by: The FreeBSD Foundation Modified: head/sys/kern/uipc_usrreq.c Modified: head/sys/kern/uipc_usrreq.c ============================================================================== --- head/sys/kern/uipc_usrreq.c Tue Oct 8 21:40:42 2019 (r353330) +++ head/sys/kern/uipc_usrreq.c Tue Oct 8 23:34:48 2019 (r353331) @@ -2318,7 +2318,8 @@ unp_internalize(struct mbuf **controlp, struct thread goto out; } - controlp = &(*controlp)->m_next; + if (*controlp != NULL) + controlp = &(*controlp)->m_next; if (CMSG_SPACE(datalen) < clen) { clen -= CMSG_SPACE(datalen); cm = (struct cmsghdr *) _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"