[Bug 237064] Fix a memory leak in pw when invoked with -V or -R
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bugzilla-noreply at freebsd.org
Sat Apr 6 20:47:53 UTC 2019
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=237064
Bug ID: 237064
Summary: Fix a memory leak in pw when invoked with -V or -R
Product: Base System
Version: CURRENT
Hardware: Any
OS: Any
Status: New
Severity: Affects Many People
Priority: ---
Component: bin
Assignee: bugs at FreeBSD.org
Reporter: momchil at xaxo.eu
Created attachment 203432
--> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=203432&action=edit
Proposed solution/patch
pw leaks memory when invoked with the -V or -R arguments. The following
example leaks memory
pw -V /etc usershow root
This does not leak any memory
pw usershow root
The memory leak is more prominent when
pw -V /etc usershow -a
is invoked as a portion of memory is leaked for each entry in the user table.
The passwd and group structures are allocated with malloc() in vnextpwent() and
vnextgrent() when the -V or -R options are used. These call pw_scan() and
gr_scan() which call pw_dup() and gr_dup(). The latter calls gr_add() which
does calls malloc(). Calls to GETPWENT(), GETPWNAM(), GETGRENT() and GETGRNAM()
are used to obtain the structures. These structures are not later released via
free(). The missing calls to free() are probably due the fact that they are not
necessary when pw is not invoked with either -V or -R arguments. In this case
the functions vnextpwent() and vnextgrent() are not used. Instead, the
functions getpwent() and getgrent() are used. These do not require the user to
free the structures.
The proposed solution: record the last structures provided by vnextpwent() and
vnextgrent() and free them upon consecutive calls. This solution is in the
spirit of getpwent() and getgrent().
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