gnome-software (5) g_realloc → g_array_maybe_expand → g_array_set_size → g_byte_array_set_size → read_cb

[errors.ubuntu.com bug bridge]

[Impact]
snapd-glib can do an invalid memory access when parsing HTTP chunked data. Found doing code inspection and testing based on crash reports.

[Test Case]
No specific trigger - just look for reduced reports on errors.ubuntu.com.

[Regression Potential]
Some risk of further breaking HTTP handling in snapd-glib. Updated algorithm tested in a test program run through valgrind to give confidence in the changes.

Error reports:

https://errors.ubuntu.com/problem/d94c431d27115bab216f9e1ea756f876e7cd933b

[Robert Ancell (robert-ancell)]

The crash report shows snapd-glib trying to allocate 2.6G of memory...

[Robert Ancell (robert-ancell)]

It looks like the cause is the HTTP chunk handling. Testing of this code showed a couple of buffer overruns, which are now fixed in snapd-glib 1.40.

[Łukasz Zemczak (sil2100)]

An upload of snapd-glib to bionic-proposed has been rejected from the upload queue for the following reason: "Unmentioned feature additions in source - are those required to fix the bug in question? If yes, please clarify on the bug. If not, please fill in a bug for the feature and attach in the changelog.".

[Łukasz Zemczak (sil2100)]

For LTS releases new features aren't necessarily a bad thing - but if there are any, those need to be properly documented with SRU paperwork if not stated otherwise by an SRU exception. The bug should include rationale as of why the change is needed in the given LTS.

[Launchpad Janitor (janitor)]

This bug was fixed in the package snapd-glib - 1.41-0ubuntu1

---------------
snapd-glib (1.41-0ubuntu1) cosmic; urgency=medium

  * New upstream release

 -- Robert Ancell <email address hidden> Fri, 01 Jun 2018 15:49:46 +1200

[Brian Murray (brian-murray)]

Hello errors.ubuntu.com, or anyone else affected,

Accepted snapd-glib into bionic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/snapd-glib/1.41-0ubuntu0.18.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-bionic to verification-done-bionic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-bionic. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Sebastien Bacher (seb128)]

1.41-0ubuntu0.18.04.1 works without visible issue

[Łukasz Zemczak (sil2100)]

The verification of the Stable Release Update for snapd-glib has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package snapd-glib - 1.41-0ubuntu0.18.04.1

---------------
snapd-glib (1.41-0ubuntu0.18.04.1) bionic; urgency=medium

  * New upstream release:
    - Fix buffer overflows reading HTTP chunked data (LP: #1740865)
    - Support new snapd API (LP: #1774565) (LP: #1774566)

 -- Robert Ancell <email address hidden> Fri, 01 Jun 2018 16:03:26 +1200