** Description changed:
+ [ Impact ]
+
+ * An explanation of the effects of the bug on users and
+
+ * justification for backporting the fix to the stable release.
+
+ * In addition, it is helpful, but not required, to include an
+ explanation of how the upload fixes this bug.
+
+ [ Test Plan ]
+
+ * detailed instructions how to reproduce the bug
+
+ * these should allow someone who is not familiar with the affected
+ package to reproduce the bug and verify that the updated package fixes
+ the problem.
+
+ * if other testing is appropriate to perform before landing this update,
+ this should also be described here.
+
+ [ Where problems could occur ]
+
+ * Think about what the upload changes in the software. Imagine the change is
+ wrong or breaks something else: how would this show up?
+
+ * It is assumed that any SRU candidate patch is well-tested before
+ upload and has a low overall risk of regression, but it's important
+ to make the effort to think about what ''could'' happen in the
+ event of a regression.
+
+ * This must '''never''' be "None" or "Low", or entirely an argument as to why
+ your upload is low risk.
+
+ * This both shows the SRU team that the risks have been considered,
+ and provides guidance to testers in regression-testing the SRU.
+
+ [ Other Info ]
+
+ * Anything else you think is useful to include
+ * Anticipate questions from users, SRU, +1 maintenance, security teams and
the Technical Board
+ * and address these questions in advance
+
+ [ Original description ]
+
upstream discussion: https://lists.thekelleys.org.uk/pipermail/dnsmasq-
discuss/2022q3/016563.html
in my journal, my dns service crash and restart just after:
Dec 04 17:18:38 dnsmasq[199333]: no servers found in
/run/NetworkManager/no-stub-resolv.conf, will retry
oops report: https://errors.ubuntu.com/oops/29cf5e2e-92b1-11ee-9bdf-
fa163ec44ecd
ubuntu jammy, dnsmasq-base 2.86-1.1ubuntu0.3
** Changed in: dnsmasq (Ubuntu Jammy)
Status: Triaged => In Progress
** Description changed:
[ Impact ]
- * An explanation of the effects of the bug on users and
+ dnsmasq "keeps an eye" on /etc/resolv.conf, and reloads it whenever the
+ file is updated. When that happens and for some reason there were no
+ "nameserver" declarations in the updated file, dnsmasq can crash.
- * justification for backporting the fix to the stable release.
+ Here is a log of a reproducer:
+ $ dig +short @127.0.0.1 ubuntu.com
+ ;; communications error to 127.0.0.1#53: timed out
+ ;; communications error to 127.0.0.1#53: connection refused
+ ;; communications error to 127.0.0.1#53: connection refused
+ ;; no servers could be reached
- * In addition, it is helpful, but not required, to include an
- explanation of how the upload fixes this bug.
+ We can see the startup, then when resolv.conf is read again and no
nameservers were found, and the crash:
+ Jan 03 13:57:13 j-dnsmasq-2045570 dnsmasq[1507]: started, version 2.86
cachesize 150
+ Jan 03 13:57:13 j-dnsmasq-2045570 dnsmasq[1507]: DNS service limited to local
subnets
+ Jan 03 13:57:13 j-dnsmasq-2045570 dnsmasq[1507]: compile time options: IPv6
GNU-getopt DBus no-UBus i18n IDN2 DHCP DHCPv6 no-Lua TFTP conntrack ipset auth
cryptohash DNSSEC loop-detect inotify dumpfile
+ Jan 03 13:57:13 j-dnsmasq-2045570 dnsmasq[1507]: reading /etc/resolv.conf
+ Jan 03 13:57:13 j-dnsmasq-2045570 dnsmasq[1507]: using nameserver
10.0.100.1#53
+ Jan 03 13:57:13 j-dnsmasq-2045570 dnsmasq[1507]: read /etc/hosts - 7 addresses
+ Jan 03 13:57:13 j-dnsmasq-2045570 systemd[1]: Started dnsmasq - A lightweight
DHCP and caching DNS server.
+ Jan 03 13:58:01 j-dnsmasq-2045570 dnsmasq[1507]: no servers found in
/etc/resolv.conf, will retry
+ Jan 03 13:58:22 j-dnsmasq-2045570 systemd[1]: dnsmasq.service: Main process
exited, code=dumped, status=11/SEGV
+ Jan 03 13:58:22 j-dnsmasq-2045570 systemd[1]: dnsmasq.service: Failed with
result 'core-dump'.
+
+ dnsmasq has provisions for this situation, we can see that in the
+ 13:58:01 message where it says it will retry, but due to this bug, it
+ crashes instead.
+
[ Test Plan ]
- * detailed instructions how to reproduce the bug
+ * detailed instructions how to reproduce the bug
- * these should allow someone who is not familiar with the affected
- package to reproduce the bug and verify that the updated package fixes
- the problem.
+ * these should allow someone who is not familiar with the affected
+ package to reproduce the bug and verify that the updated package fixes
+ the problem.
- * if other testing is appropriate to perform before landing this update,
- this should also be described here.
+ * if other testing is appropriate to perform before landing this update,
+ this should also be described here.
[ Where problems could occur ]
- * Think about what the upload changes in the software. Imagine the change is
- wrong or breaks something else: how would this show up?
+ * Think about what the upload changes in the software. Imagine the change is
+ wrong or breaks something else: how would this show up?
- * It is assumed that any SRU candidate patch is well-tested before
- upload and has a low overall risk of regression, but it's important
- to make the effort to think about what ''could'' happen in the
- event of a regression.
+ * It is assumed that any SRU candidate patch is well-tested before
+ upload and has a low overall risk of regression, but it's important
+ to make the effort to think about what ''could'' happen in the
+ event of a regression.
- * This must '''never''' be "None" or "Low", or entirely an argument as to why
- your upload is low risk.
+ * This must '''never''' be "None" or "Low", or entirely an argument as to why
+ your upload is low risk.
- * This both shows the SRU team that the risks have been considered,
- and provides guidance to testers in regression-testing the SRU.
+ * This both shows the SRU team that the risks have been considered,
+ and provides guidance to testers in regression-testing the SRU.
[ Other Info ]
-
- * Anything else you think is useful to include
- * Anticipate questions from users, SRU, +1 maintenance, security teams and
the Technical Board
- * and address these questions in advance
+
+ * Anything else you think is useful to include
+ * Anticipate questions from users, SRU, +1 maintenance, security teams and
the Technical Board
+ * and address these questions in advance
[ Original description ]
upstream discussion: https://lists.thekelleys.org.uk/pipermail/dnsmasq-
discuss/2022q3/016563.html
in my journal, my dns service crash and restart just after:
Dec 04 17:18:38 dnsmasq[199333]: no servers found in
/run/NetworkManager/no-stub-resolv.conf, will retry
oops report: https://errors.ubuntu.com/oops/29cf5e2e-92b1-11ee-9bdf-
fa163ec44ecd
ubuntu jammy, dnsmasq-base 2.86-1.1ubuntu0.3
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You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to dnsmasq in Ubuntu.
https://bugs.launchpad.net/bugs/2045570
Title:
dnsmasq crash when no servers in resolv.conf
Status in dnsmasq package in Ubuntu:
Fix Released
Status in dnsmasq source package in Jammy:
In Progress
Bug description:
[ Impact ]
dnsmasq "keeps an eye" on /etc/resolv.conf, and reloads it whenever
the file is updated. When that happens and for some reason there were
no "nameserver" declarations in the updated file, dnsmasq can crash.
Here is a log of a reproducer:
$ dig +short @127.0.0.1 ubuntu.com
;; communications error to 127.0.0.1#53: timed out
;; communications error to 127.0.0.1#53: connection refused
;; communications error to 127.0.0.1#53: connection refused
;; no servers could be reached
We can see the startup, then when resolv.conf is read again and no
nameservers were found, and the crash:
Jan 03 13:57:13 j-dnsmasq-2045570 dnsmasq[1507]: started, version 2.86
cachesize 150
Jan 03 13:57:13 j-dnsmasq-2045570 dnsmasq[1507]: DNS service limited to local
subnets
Jan 03 13:57:13 j-dnsmasq-2045570 dnsmasq[1507]: compile time options: IPv6
GNU-getopt DBus no-UBus i18n IDN2 DHCP DHCPv6 no-Lua TFTP conntrack ipset auth
cryptohash DNSSEC loop-detect inotify dumpfile
Jan 03 13:57:13 j-dnsmasq-2045570 dnsmasq[1507]: reading /etc/resolv.conf
Jan 03 13:57:13 j-dnsmasq-2045570 dnsmasq[1507]: using nameserver
10.0.100.1#53
Jan 03 13:57:13 j-dnsmasq-2045570 dnsmasq[1507]: read /etc/hosts - 7 addresses
Jan 03 13:57:13 j-dnsmasq-2045570 systemd[1]: Started dnsmasq - A lightweight
DHCP and caching DNS server.
Jan 03 13:58:01 j-dnsmasq-2045570 dnsmasq[1507]: no servers found in
/etc/resolv.conf, will retry
Jan 03 13:58:22 j-dnsmasq-2045570 systemd[1]: dnsmasq.service: Main process
exited, code=dumped, status=11/SEGV
Jan 03 13:58:22 j-dnsmasq-2045570 systemd[1]: dnsmasq.service: Failed with
result 'core-dump'.
dnsmasq has provisions for this situation, we can see that in the
13:58:01 message where it says it will retry, but due to this bug, it
crashes instead.
[ Test Plan ]
* detailed instructions how to reproduce the bug
* these should allow someone who is not familiar with the affected
package to reproduce the bug and verify that the updated package fixes
the problem.
* if other testing is appropriate to perform before landing this update,
this should also be described here.
[ Where problems could occur ]
* Think about what the upload changes in the software. Imagine the change is
wrong or breaks something else: how would this show up?
* It is assumed that any SRU candidate patch is well-tested before
upload and has a low overall risk of regression, but it's important
to make the effort to think about what ''could'' happen in the
event of a regression.
* This must '''never''' be "None" or "Low", or entirely an argument as to why
your upload is low risk.
* This both shows the SRU team that the risks have been considered,
and provides guidance to testers in regression-testing the SRU.
[ Other Info ]
* Anything else you think is useful to include
* Anticipate questions from users, SRU, +1 maintenance, security teams and
the Technical Board
* and address these questions in advance
[ Original description ]
upstream discussion:
https://lists.thekelleys.org.uk/pipermail/dnsmasq-
discuss/2022q3/016563.html
in my journal, my dns service crash and restart just after:
Dec 04 17:18:38 dnsmasq[199333]: no servers found in
/run/NetworkManager/no-stub-resolv.conf, will retry
oops report: https://errors.ubuntu.com/oops/29cf5e2e-92b1-11ee-9bdf-
fa163ec44ecd
ubuntu jammy, dnsmasq-base 2.86-1.1ubuntu0.3
To manage notifications about this bug go to:
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