[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: [libvirt] [PATCH] daemon: Plug memory leaks



On 04/12/2012 04:37 PM, Daniel P. Berrange wrote:
On Thu, Apr 12, 2012 at 03:24:08PM +0800, Alex Jia wrote:
Detected by valgrind. Leaks are introduced in commit 6e6e9be.

* daemon/libvirtd-config.c (macro GET_CONF_STR): fix memory leaks.

How to reproduce?

% make&&  make -C tests check TESTS=libvirtdconftest
% cd tests&&  valgrind -v --leak-check=full ./libvirtdconftest

actual result:

==11008== 185 bytes in 5 blocks are definitely lost in loss record 3 of 5
==11008==    at 0x4A05FDE: malloc (vg_replace_malloc.c:236)
==11008==    by 0x39CF07F6E1: strdup (strdup.c:43)
==11008==    by 0x406626: daemonConfigLoadOptions (libvirtd-config.c:438)
==11008==    by 0x406800: daemonConfigLoadData (libvirtd-config.c:492)
==11008==    by 0x403CCF: testCorrupt (libvirtdconftest.c:110)
==11008==    by 0x404FAD: virtTestRun (testutils.c:145)
==11008==    by 0x403A34: mymain (libvirtdconftest.c:219)
==11008==    by 0x404687: virtTestMain (testutils.c:700)
==11008==    by 0x39CF01ECDC: (below main) (libc-start.c:226)
==11008==
==11008== LEAK SUMMARY:
==11008==    definitely lost: 185 bytes in 5 blocks

Signed-off-by: Alex Jia<ajia redhat com>
---
  daemon/libvirtd-config.c |    1 +
  1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/daemon/libvirtd-config.c b/daemon/libvirtd-config.c
index 4d041f0..0a4323a 100644
--- a/daemon/libvirtd-config.c
+++ b/daemon/libvirtd-config.c
@@ -152,6 +152,7 @@ checkType (virConfValuePtr p, const char *filename,
                  virReportOOMError();                                    \
                  goto error;                                             \
              }                                                           \
+            VIR_FREE(data->var_name);                                   \
          }                                                               \
      } while (0)
Errr, no. Please look at the context of what's going on, rather than
just blindly adding code to free a block at the point where valgrind
shows the allocation.

The full context to this diff

#define GET_CONF_STR(conf, filename, var_name)                          \
     do {                                                                \
         virConfValuePtr p = virConfGetValue (conf, #var_name);          \
         if (p) {                                                        \
             if (checkType (p, filename, #var_name, VIR_CONF_STRING)<  0) \
                 goto error;                                             \
             VIR_FREE(data->var_name);                                   \
             if (!(data->var_name = strdup (p->str))) {                  \
                 virReportOOMError();                                    \
                 goto error;                                             \
             }                                                           \
         }                                                               \
     } while (0)


Your suggested change means we would be free'ing the config file before
we have even used it.

If you look at this line:
Yeah.
==11008==    by 0x406626: daemonConfigLoadOptions (libvirtd-config.c:438)
You'll see it matches:

     GET_CONF_STR (conf, filename, host_uuid);

There are no leak reports for other uses of GET_CONF_STR, so this suggests
that 'host_uuid' is not being freed. Check daemonConfigFree and you'll see
this is indeed missing
Yeah, it's a little weird, the previous codes also haven't free 'host_uuid', but valgrind hasn't complains memory leak.

Thanks for your review,
Alex
Daniel


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]