ls: plug a per-argument leak

Using ls -l on an SELinux-enabled system would leak one SELinux
context string per non-empty-directory command-line argument.
* src/ls.c (free_ent): New function, factored out of...
(clear_files): ...here.  Use it.
(extract_dirs_from_files): Call free_ent (f), rather than simply
free (f->name).  The latter failed to free the possibly-malloc'd
linkname and scontext members, and thus could leak one of those
strings per command-line argument.
* THANKS.in: Update.
* NEWS (Bug fixes): Mention it.
Reported by Juraj Marko in http://bugzilla.redhat.com/751974.

3 files changed, 16 insertions, 6 deletions

diff --git a/NEWS b/NEWS
index 1b0f2f5e9..de3888ddb 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,10 @@ GNU coreutils NEWS                                    -*- outline -*-
   --block-size=1KiB, a new long option --kibibyte stands for -k.
   [bug introduced in coreutils-4.5.4]
 
+  ls -l would leak a little memory (security context string) for each
+  nonempty directory listed on the command line, when using SELinux.
+  [bug probably introduced in coreutils-6.10 with SELinux support]
+
   rm -rf DIR would fail with "Device or resource busy" on Cygwin with NWFS
   and NcFsd file systems.  This did not affect Unix/Linux-based kernels.
   [bug introduced in coreutils-8.0, when rm began using fts]
diff --git a/THANKS.in b/THANKS.in
index 83a78649a..ccdbc84b6 100644
--- a/THANKS.in
+++ b/THANKS.in
@@ -311,6 +311,7 @@ Juan M. Guerrero                    st001906@hrz1.hrz.tu-darmstadt.de
 Julian Bradfield                    jcb@inf.ed.ac.uk
 Jungshik Shin                       jshin@pantheon.yale.edu
 Jürgen Fluk                         louis@dachau.marco.de
+Juraj Marko                         jmarko@redhat.com
 Jurriaan                            thunder7@xs4all.nl
 Justin Pryzby                       justinpryzby@users.sourceforge.net
 jvogel                              jvogel@linkny.com
diff --git a/src/ls.c b/src/ls.c
index b8a09b3df..96f7c987b 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -2715,8 +2715,16 @@ has_capability (char const *name ATTRIBUTE_UNUSED)
 
 /* Enter and remove entries in the table `cwd_file'.  */
 
-/* Empty the table of files.  */
+static void
+free_ent (struct fileinfo *f)
+{
+  free (f->name);
+  free (f->linkname);
+  if (f->scontext != UNKNOWN_SECURITY_CONTEXT)
+    freecon (f->scontext);
+}
 
+/* Empty the table of files.  */
 static void
 clear_files (void)
 {
@@ -2725,10 +2733,7 @@ clear_files (void)
   for (i = 0; i < cwd_n_used; i++)
     {
       struct fileinfo *f = sorted_file[i];
-      free (f->name);
-      free (f->linkname);
-      if (f->scontext != UNKNOWN_SECURITY_CONTEXT)
-        freecon (f->scontext);
+      free_ent (f);
     }
 
   cwd_n_used = 0;
@@ -3164,7 +3169,7 @@ extract_dirs_from_files (char const *dirname, bool command_line_arg)
               free (name);
             }
           if (f->filetype == arg_directory)
-            free (f->name);
+            free_ent (f);
         }
     }