commit c1f86a33ca32e26a9d6e29fc961e5ecb5e2e5eb4
Author: Daniel Alvarez <dalvarez@redhat.com>
Date:   Fri Jun 29 09:44:55 2018 +0200

    getifaddrs: Don't return ifa entries with NULL names [BZ #21812]
    
    A lookup operation in map_newlink could turn into an insert because of
    holes in the interface part of the map.  This leads to incorrectly set
    the name of the interface to NULL when the interface is not present
    for the address being processed (most likely because the interface was
    added between the RTM_GETLINK and RTM_GETADDR calls to the kernel).
    When such changes are detected by the kernel, it'll mark the dump as
    "inconsistent" by setting NLM_F_DUMP_INTR flag on the next netlink
    message.
    
    This patch checks this condition and retries the whole operation.
    Hopes are that next time the interface corresponding to the address
    entry is present in the list and correct name is returned.

diff --git a/sysdeps/unix/sysv/linux/ifaddrs.c b/sysdeps/unix/sysv/linux/ifaddrs.c
index c87e594e30a314fe..b1329dc4d4c63529 100644
--- a/sysdeps/unix/sysv/linux/ifaddrs.c
+++ b/sysdeps/unix/sysv/linux/ifaddrs.c
@@ -369,6 +369,14 @@ getifaddrs_internal (struct ifaddrs **ifap)
 	  if ((pid_t) nlh->nlmsg_pid != nh.pid || nlh->nlmsg_seq != nlp->seq)
 	    continue;
 
+	  /* If the dump got interrupted, we can't rely on the results
+	     so try again. */
+	  if (nlh->nlmsg_flags & NLM_F_DUMP_INTR)
+	    {
+	      result = -EAGAIN;
+	      goto exit_free;
+	    }
+
 	  if (nlh->nlmsg_type == NLMSG_DONE)
 	    break;		/* ok */