** Description changed:
= Summary =
The version of Upstart in precise is affected by a bug in the way that
".override" [1] file handling is performed.
If a job has an override file ("/etc/init/*.override") and that override
file is deleted before the corresponding job configuration file
("/etc/init/*.conf"), there is a possibility of a crash.
== Explanation ==
When a "/etc/init/*.override" file is deleted, Upstart will
automatically detect this and reload the corresponding
"/etc/init/*.conf" file.
However, if the ".conf" file (which the ".override" file corresponded
to) is deleted at the same time Upstart attempts to read the ".conf"
file, an assertion failure could result.
-
= Code Specifics =
The erroneous function is "conf_delete_handler()" which is called
whenever a file Upstart is watching gets deleted. The end of this
function calls conf_reload_path() but although it logs an error message,
it does not consume the error object that gets raised when
conf_reload_path() fails.
-
= Affected Releases =
This bug is only present in precise:
- Upstart override handling was introduced in Upstart v1.3:
- Precise currently uses Upstart 1.5-0ubuntu7.2 (and hence is affected).
- Lucid currently uses Upstart 0.6.5-8 (hence, not affected).
- Trusty and Vivid use much newer versions of the Upstart which no
- longer contain the problematic code.
-
+ longer contain the problematic code.
= Fix =
The fix is simply to have conf_delete_handler() consume the error object
(by freeing it) when conf_reload_path() fails.
-
= Test Case =
A reliable test case is unfortunately not possible to create, since the
problem comes down to Upstart racing with the deletion of the ".conf"
file.
However, the patch is small and it can be seen that every other failing
call to conf_reload_path() free's the resulting error object.
+ = Workarounds =
+
+ The problem is only manifested if ".conf" and the ".override" file get
+ deleted one after another, with the ".override" file being deleted
+ first. This implies the following work-arounds to avoid the problem if
+ you wish to delete both files "at the same time":
+
+ 1) Ensure the ".conf" file is deleted first.
+
+ 2) Delete the ".override" file first, and then wait for a small period
+ of time before deleting the corresponding ".conf" file.
+
+ 3) Delete the ".override" file first, then call "sudo initctl reload-
+ configuration" and then delete the corresponding ".conf" file.
= Regression Potential =
None expected. The problem is difficult to trigger anwyay and the patch
can be seen to correct (what is now) an obvious coding error.
-
[1] - http://upstart.ubuntu.com/cookbook/#override-file
= Original Description =
ubuntu-touch livefs builds have started killing upstart in the host
system (in this case, precise, although a similar bug appears to be
present in current versions). The livefs build completes, but the host
dies shortly after launchpad-buildd starts trying to remove the build
chroot. The kernel log looks like this:
Mar 10 13:46:55 allspice kernel: [3743880.621603] init:
/home/buildd/build-LIVEFSBUILD-22254/chroot-autobuild/build/chroot/etc/init/tty1.conf:
Unable to reload configuration after override deletion
Mar 10 13:46:55 allspice kernel: [3743880.642455] init: file.c:110: Unhandled
error from nih_file_read: No such file or directory
Mar 10 13:46:55 allspice kernel: [3743880.754281] init: Caught abort, core
dumped
Mar 10 13:46:55 allspice kernel: [3743880.754375] init: file.c:110: Unhandled
error from nih_file_read: No such file or directory
Mar 10 13:46:55 allspice kernel: [3743880.757830] init: Caught abort, core
dumped
This appears to be because a couple of functions call conf_reload_path,
which may leave an nih_error in place if nih_file_read fails, but then
do not dispose of the nih_error. The pattern near the end of
conf_file_visitor (in precise) is probably appropriate.
We're working around this to some extent in livecd-rootfs by removing
the .override files first, but it should never be possible for a chroot
to crash the host's init.
** Description changed:
= Summary =
The version of Upstart in precise is affected by a bug in the way that
".override" [1] file handling is performed.
If a job has an override file ("/etc/init/*.override") and that override
file is deleted before the corresponding job configuration file
("/etc/init/*.conf"), there is a possibility of a crash.
== Explanation ==
When a "/etc/init/*.override" file is deleted, Upstart will
automatically detect this and reload the corresponding
"/etc/init/*.conf" file.
However, if the ".conf" file (which the ".override" file corresponded
to) is deleted at the same time Upstart attempts to read the ".conf"
file, an assertion failure could result.
= Code Specifics =
The erroneous function is "conf_delete_handler()" which is called
whenever a file Upstart is watching gets deleted. The end of this
function calls conf_reload_path() but although it logs an error message,
it does not consume the error object that gets raised when
conf_reload_path() fails.
= Affected Releases =
This bug is only present in precise:
- Upstart override handling was introduced in Upstart v1.3:
- Precise currently uses Upstart 1.5-0ubuntu7.2 (and hence is affected).
- Lucid currently uses Upstart 0.6.5-8 (hence, not affected).
- Trusty and Vivid use much newer versions of the Upstart which no
longer contain the problematic code.
= Fix =
The fix is simply to have conf_delete_handler() consume the error object
(by freeing it) when conf_reload_path() fails.
= Test Case =
A reliable test case is unfortunately not possible to create, since the
problem comes down to Upstart racing with the deletion of the ".conf"
file.
However, the patch is small and it can be seen that every other failing
call to conf_reload_path() free's the resulting error object.
= Workarounds =
- The problem is only manifested if ".conf" and the ".override" file get
- deleted one after another, with the ".override" file being deleted
+ The problem is only manifested if the ".conf" and the ".override" file
+ get deleted one after another, with the ".override" file being deleted
first. This implies the following work-arounds to avoid the problem if
you wish to delete both files "at the same time":
1) Ensure the ".conf" file is deleted first.
2) Delete the ".override" file first, and then wait for a small period
of time before deleting the corresponding ".conf" file.
3) Delete the ".override" file first, then call "sudo initctl reload-
configuration" and then delete the corresponding ".conf" file.
= Regression Potential =
None expected. The problem is difficult to trigger anwyay and the patch
can be seen to correct (what is now) an obvious coding error.
[1] - http://upstart.ubuntu.com/cookbook/#override-file
= Original Description =
ubuntu-touch livefs builds have started killing upstart in the host
system (in this case, precise, although a similar bug appears to be
present in current versions). The livefs build completes, but the host
dies shortly after launchpad-buildd starts trying to remove the build
chroot. The kernel log looks like this:
Mar 10 13:46:55 allspice kernel: [3743880.621603] init:
/home/buildd/build-LIVEFSBUILD-22254/chroot-autobuild/build/chroot/etc/init/tty1.conf:
Unable to reload configuration after override deletion
Mar 10 13:46:55 allspice kernel: [3743880.642455] init: file.c:110: Unhandled
error from nih_file_read: No such file or directory
Mar 10 13:46:55 allspice kernel: [3743880.754281] init: Caught abort, core
dumped
Mar 10 13:46:55 allspice kernel: [3743880.754375] init: file.c:110: Unhandled
error from nih_file_read: No such file or directory
Mar 10 13:46:55 allspice kernel: [3743880.757830] init: Caught abort, core
dumped
This appears to be because a couple of functions call conf_reload_path,
which may leave an nih_error in place if nih_file_read fails, but then
do not dispose of the nih_error. The pattern near the end of
conf_file_visitor (in precise) is probably appropriate.
We're working around this to some extent in livecd-rootfs by removing
the .override files first, but it should never be possible for a chroot
to crash the host's init.
--
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to upstart in Ubuntu.
https://bugs.launchpad.net/bugs/1430403
Title:
[SRU] ubuntu-touch livefs builds kill upstart in host
Status in upstart package in Ubuntu:
In Progress
Status in upstart source package in Precise:
New
Bug description:
= Summary =
The version of Upstart in precise is affected by a bug in the way that
".override" [1] file handling is performed.
If a job has an override file ("/etc/init/*.override") and that
override file is deleted before the corresponding job configuration
file ("/etc/init/*.conf"), there is a possibility of a crash.
== Explanation ==
When a "/etc/init/*.override" file is deleted, Upstart will
automatically detect this and reload the corresponding
"/etc/init/*.conf" file.
However, if the ".conf" file (which the ".override" file corresponded
to) is deleted at the same time Upstart attempts to read the ".conf"
file, an assertion failure could result.
= Code Specifics =
The erroneous function is "conf_delete_handler()" which is called
whenever a file Upstart is watching gets deleted. The end of this
function calls conf_reload_path() but although it logs an error
message, it does not consume the error object that gets raised when
conf_reload_path() fails.
= Affected Releases =
This bug is only present in precise:
- Upstart override handling was introduced in Upstart v1.3:
- Precise currently uses Upstart 1.5-0ubuntu7.2 (and hence is affected).
- Lucid currently uses Upstart 0.6.5-8 (hence, not affected).
- Trusty and Vivid use much newer versions of the Upstart which no
longer contain the problematic code.
= Fix =
The fix is simply to have conf_delete_handler() consume the error
object (by freeing it) when conf_reload_path() fails.
= Test Case =
A reliable test case is unfortunately not possible to create, since the
problem comes down to Upstart racing with the deletion of the ".conf"
file.
However, the patch is small and it can be seen that every other
failing call to conf_reload_path() free's the resulting error object.
= Workarounds =
The problem is only manifested if the ".conf" and the ".override" file
get deleted one after another, with the ".override" file being deleted
first. This implies the following work-arounds to avoid the problem if
you wish to delete both files "at the same time":
1) Ensure the ".conf" file is deleted first.
2) Delete the ".override" file first, and then wait for a small period
of time before deleting the corresponding ".conf" file.
3) Delete the ".override" file first, then call "sudo initctl reload-
configuration" and then delete the corresponding ".conf" file.
= Regression Potential =
None expected. The problem is difficult to trigger anwyay and the
patch can be seen to correct (what is now) an obvious coding error.
[1] - http://upstart.ubuntu.com/cookbook/#override-file
= Original Description =
ubuntu-touch livefs builds have started killing upstart in the host
system (in this case, precise, although a similar bug appears to be
present in current versions). The livefs build completes, but the
host dies shortly after launchpad-buildd starts trying to remove the
build chroot. The kernel log looks like this:
Mar 10 13:46:55 allspice kernel: [3743880.621603] init:
/home/buildd/build-LIVEFSBUILD-22254/chroot-autobuild/build/chroot/etc/init/tty1.conf:
Unable to reload configuration after override deletion
Mar 10 13:46:55 allspice kernel: [3743880.642455] init: file.c:110: Unhandled
error from nih_file_read: No such file or directory
Mar 10 13:46:55 allspice kernel: [3743880.754281] init: Caught abort, core
dumped
Mar 10 13:46:55 allspice kernel: [3743880.754375] init: file.c:110: Unhandled
error from nih_file_read: No such file or directory
Mar 10 13:46:55 allspice kernel: [3743880.757830] init: Caught abort, core
dumped
This appears to be because a couple of functions call
conf_reload_path, which may leave an nih_error in place if
nih_file_read fails, but then do not dispose of the nih_error. The
pattern near the end of conf_file_visitor (in precise) is probably
appropriate.
We're working around this to some extent in livecd-rootfs by removing
the .override files first, but it should never be possible for a
chroot to crash the host's init.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/upstart/+bug/1430403/+subscriptions
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