Your message dated Mon, 23 May 2016 12:26:50 +0200
with message-id
<CAOO6c=w=HNiS6b6XGpeWk83c3YJ=pMFk8PT1vvW0qN5NS=m...@mail.gmail.com>
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has caused the Debian Bug report #812984,
regarding CVE-2016-0738: Fix memory/socket leak in proxy on truncated SLO/DLO
GET
to be marked as done.
This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.
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--
812984: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=812984
Debian Bug Tracking System
Contact [email protected] with problems
--- Begin Message ---
Package: swift
Version: 2.5.0-2
Severity: important
Tags: security
https://github.com/openstack/swift/commit/8c1976aa771f8c43c5dbe676bd9a5efc69f09eae
When a client disconnected while consuming an SLO or DLO GET response,
the proxy would leak a socket. This could be observed via strace as a
socket that had shutdown() called on it, but was never closed. It
could also be observed by counting entries in /proc/<pid>/fd, where
<pid> is the pid of a proxy server worker process.
This is due to a memory leak in SegmentedIterable. A SegmentedIterable
has an 'app_iter' attribute, which is a generator. That generator
references 'self' (the SegmentedIterable object). This creates a
cyclic reference: the generator refers to the SegmentedIterable, and
the SegmentedIterable refers to the generator.
Python can normally handle cyclic garbage; reference counting won't
reclaim it, but the garbage collector will. However, objects with
finalizers will stop the garbage collector from collecting them* and
the cycle of which they are part.
For most objects, "has finalizer" is synonymous with "has a __del__
method". However, a generator has a finalizer once it's started
running and before it finishes: basically, while it has stack frames
associated with it**.
When a client disconnects mid-stream, we get a memory leak. We have
our SegmentedIterable object (call it "si"), and its associated
generator. si.app_iter is the generator, and the generator closes over
si, so we have a cycle; and the generator has started but not yet
finished, so the generator needs finalization; hence, the garbage
collector won't ever clean it up.
The socket leak comes in because the generator *also* refers to the
request's WSGI environment, which contains wsgi.input, which
ultimately refers to a _socket object from the standard
library. Python's _socket objects only close their underlying file
descriptor when their reference counts fall to 0***.
This commit makes SegmentedIterable.close() call
self.app_iter.close(), thereby unwinding its generator's stack and
making it eligible for garbage collection.
* in Python < 3.4, at least. See PEP 442.
** see PyGen_NeedsFinalizing() in Objects/genobject.c and also
has_finalizer() in Modules/gcmodule.c in Python.
*** see sock_dealloc() in Modules/socketmodule.c in Python. See
sock_close() in the same file for the other half of the sad
story.
-- System Information:
Debian Release: stretch/sid
APT prefers unstable
APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Kernel: Linux 4.3.0-1-amd64 (SMP w/1 CPU core)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
Versions of packages swift depends on:
ii python-swift 2.5.0-2
pn python:any <none>
swift recommends no packages.
swift suggests no packages.
-- no debconf information
--- End Message ---
--- Begin Message ---
Version: 2.5.0-3
--- End Message ---
