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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.

(cherry picked from commit c1f86a33ca)
This commit is contained in:
Daniel Alvarez 2018-06-29 17:23:52 +02:00 committed by Florian Weimer
parent 4e0847afce
commit 4476d16b03
3 changed files with 16 additions and 0 deletions
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7
ChangeLog
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@ -1,3 +1,10 @@
2018-06-29 Daniel Alvarez <dalvarez@redhat.com>
Jakub Sitnicki <jkbs@redhat.com>
[BZ #21812]
* sysdeps/unix/sysv/linux/ifaddrs.c (getifaddrs_internal): Retry
on NLM_F_DUMP_INTR.
2018-06-28 Florian Weimer <fweimer@redhat.com>
[BZ #23349]

1
NEWS
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@ -45,6 +45,7 @@ The following bugs are resolved with this release:
[18018] Additional $ORIGIN handling issues (CVE-2011-0536)
[20419] files with large allocated notes crash in open_verify
[21269] i386 sigaction sa_restorer handling is wrong
[21812] getifaddrs: Don't return ifa entries with NULL names
[21942] _dl_dst_substitute incorrectly handles $ORIGIN: with AT_SECURE=1
[22342] NSCD not properly caching netgroup
[22638] sparc: static binaries are broken if glibc is built by gcc

8
sysdeps/unix/sysv/linux/ifaddrs.c
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@ -370,6 +370,14 @@ 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 */