[libvirt] [PATCH 5/n] security: plug memory leak

[Eric Blake]

security_context_t happens to be a typedef for char*, and happens to
begin with a string usable as a raw context string.  But in reality,
it is an opaque type that may or may not have additional information
after the first NUL byte, where that additional information can
include pointers that can only be freed via freecon().

Proof is from this valgrind run of daemon/libvirtd:

==6028== 839,169 (40 direct, 839,129 indirect) bytes in 1 blocks are definitely lost in loss record 274 of 274
==6028==    at 0x4A0515D: malloc (vg_replace_malloc.c:195)
==6028==    by 0x3022E0D48C: selabel_open (label.c:165)
==6028==    by 0x3022E11646: matchpathcon_init_prefix (matchpathcon.c:296)
==6028==    by 0x3022E1190D: matchpathcon (matchpathcon.c:317)
==6028==    by 0x4F9D842: SELinuxRestoreSecurityFileLabel (security_selinux.c:382)

800k is a lot of memory to be leaking.

* src/security/security_selinux.c
(SELinuxReserveSecurityLabel, SELinuxGetSecurityProcessLabel)
(SELinuxRestoreSecurityFileLabel): Use correct function to free
security_context_t.
---
 src/security/security_selinux.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/security/security_selinux.c b/src/security/security_selinux.c
index 996177a..2a45172 100644
--- a/src/security/security_selinux.c
+++ b/src/security/security_selinux.c
@@ -239,7 +239,7 @@ SELinuxReserveSecurityLabel(virSecurityDriverPtr drv ATTRIBUTE_UNUSED,
     }

     ctx = context_new(pctx);
-    VIR_FREE(pctx);
+    freecon(pctx);
     if (!ctx)
         goto err;

@@ -298,11 +298,12 @@ SELinuxGetSecurityProcessLabel(virSecurityDriverPtr drv ATTRIBUTE_UNUSED,
                                _("security label exceeds "
                                  "maximum length: %d"),
                                VIR_SECURITY_LABEL_BUFLEN - 1);
+        freecon(ctx);
         return -1;
     }

     strcpy(sec->label, (char *) ctx);
-    VIR_FREE(ctx);
+    freecon(ctx);

     sec->enforcing = security_getenforce();
     if (sec->enforcing == -1) {
@@ -387,7 +388,7 @@ SELinuxRestoreSecurityFileLabel(const char *path)
     }

 err:
-    VIR_FREE(fcon);
+    freecon(fcon);
     VIR_FREE(newpath);
     return rc;
 }
-- 
1.7.3.2