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Bug 1358467 - memory leak when creating hdr objects
Summary: memory leak when creating hdr objects
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: rpm
Version: 7.2
Hardware: All
OS: Linux
Target Milestone: rc
: ---
Assignee: Florian Festi
QA Contact: Jan Blazek
Depends On:
TreeView+ depends on / blocked
Reported: 2016-07-20 18:47 UTC by Tasos Papaioannou
Modified: 2017-08-01 19:33 UTC (History)
1 user (show)

Fixed In Version: rpm-4.11.3-22.el7
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
: 1438811 (view as bug list)
Last Closed: 2017-08-01 19:33:33 UTC
Target Upstream Version:

Attachments (Terms of Use)
valgrind memory leak output (470.54 KB, text/plain)
2016-07-20 18:47 UTC, Tasos Papaioannou
no flags Details
proposed patch (602 bytes, patch)
2016-07-25 18:36 UTC, Tasos Papaioannou
no flags Details | Diff

System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2017:2160 0 normal SHIPPED_LIVE rpm bug fix and enhancement update 2017-08-01 18:17:27 UTC

Description Tasos Papaioannou 2016-07-20 18:47:17 UTC
Created attachment 1182219 [details]
valgrind memory leak output

Description of problem:

I have a python script that calls rpm.readHeaderListFromFile() to check rpm headers. When calling this method iteratively over rpms in a yum repository, the python process' heap grows continuously. There appears to be a memory leak when creating the header object in librpm. A simple reproducer:

# cat rpm_hdr_test.py 
import rpm

for i in xrange(1000):
    hdr1 = rpm._rpm.hdr()

Running a memory leak test w/ valgrind:

# valgrind --leak-check=full --time-stamp=yes --log-file=rpm_hdr.log python rpm_hdr_test.py

shows the following:

==00:00:00:06.733 19733== 296,000 (40,000 direct, 256,000 indirect) bytes in 1,000 blocks are definitely lost in loss record 1,935 of 1,935
==00:00:00:06.733 19733==    at 0x4C2B974: calloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==00:00:00:06.733 19733==    by 0xDA8E2EE: rcalloc (rpmmalloc.c:55)
==00:00:00:06.733 19733==    by 0xCE38951: headerCreate (header.c:168)
==00:00:00:06.733 19733==    by 0xCC14FD4: hdr_new (header-py.c:394)
==00:00:00:06.733 19733==    by 0x4ED4E52: type_call (typeobject.c:729)
==00:00:00:06.733 19733==    by 0x4E7F0C2: PyObject_Call (abstract.c:2529)
==00:00:00:06.733 19733==    by 0x4F1338B: do_call (ceval.c:4316)
==00:00:00:06.733 19733==    by 0x4F1338B: call_function (ceval.c:4121)
==00:00:00:06.733 19733==    by 0x4F1338B: PyEval_EvalFrameEx (ceval.c:2740)
==00:00:00:06.733 19733==    by 0x4F171EC: PyEval_EvalCodeEx (ceval.c:3330)
==00:00:00:06.733 19733==    by 0x4F172F1: PyEval_EvalCode (ceval.c:689)
==00:00:00:06.733 19733==    by 0x4F3072E: run_mod (pythonrun.c:1374)
==00:00:00:06.733 19733==    by 0x4F318ED: PyRun_FileExFlags (pythonrun.c:1360)
==00:00:00:06.733 19733==    by 0x4F32B78: PyRun_SimpleFileExFlags (pythonrun.c:952)

Full log file is attached.

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1.) Create and deallocate multiple hdr objects in python with rpm.readHeaderListFromFile().
2.) See increasing heap size throughout lifetime of process.

Actual results:

Memory leak when creating hdr objects.

Expected results:

No memory leak.

Additional info:

See attached valgrind log.

Comment 3 Tasos Papaioannou 2016-07-25 18:36:02 UTC
Created attachment 1183913 [details]
proposed patch

In python/header-py.c: hdr_new -> headerNew -> headerCreate in lib/header.c. headderCreate calls headerLink to increment h->nrefs once, then hdr_Wrap in python/header-py.c calls headerLink again when wrapping the C header object in a Python object, so h->nrefs is now 2.

When the Python object is deallocated, hdr_dealloc calls headerFree, which calls headerUnlink once and then quits without freeing memory if h->nrefs > 0, leading to a memory leak in Python.

I've attached a test patch which resolves the issue in my testing, to call headerUnlink once in hdr_new between the calls to headerNew and hdr_Wrap. I haven't verified whether this patch works with other code paths that call hdr_new other than "hdr1=rpm.hdr()", so it may be necessary to do this for only some of the if/else blocks in hdr_new.

Comment 4 Florian Festi 2016-10-21 10:01:41 UTC
Thanks for hunting this down. Turns out the reference counting of header objects is messed up at even more places in the Python binding. This is now fixed up stream as commit 40326b5724b0cd55a21b2d86eeef344e4826f863.

Comment 8 errata-xmlrpc 2017-08-01 19:33:33 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.


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