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Re: [libvirt] [PATCH] network: avoid memory leak on cleanup



On 07/15/2011 03:03 PM, Alex Jia wrote:
On 07/15/2011 02:49 PM, Matthias Bolte wrote:
2011/7/15  <ajia redhat com>:
* src/network/bridge_driver.c: Fix memory leak on cleanup section from
 networkGetBridgeName function.
---
 src/network/bridge_driver.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
index 0a12bc0..59e780d 100644
--- a/src/network/bridge_driver.c
+++ b/src/network/bridge_driver.c
@@ -2474,7 +2474,8 @@ static char *networkGetBridgeName(virNetworkPtr net) {
 cleanup:
    if (network)
        virNetworkObjUnlock(network);
-    return bridge;
+    VIR_FREE(bridge);
+    return NULL;
 }

 static int networkGetAutostart(virNetworkPtr net,
NACK. Now networkGetBridgeName returns NULL always, that's wrong.

Why do you think that there is a leak?

Detected in valgrind run:
==9020== 7 bytes in 1 blocks are definitely lost in loss record 1 of 26
==9020==    at 0x4A05FDE: malloc (vg_replace_malloc.c:236)
==9020==    by 0x386A314B3D: xdr_string (in /lib64/libc-2.12.so)
==9020==    by 0x4CFC0AD: xdr_remote_nonnull_string (remote_protocol.c:30)
==9020==    by 0x4CFCC08: xdr_remote_network_get_bridge_name_ret (remote_protocol.c:1999)
==9020==    by 0x4D06FC1: virNetMessageDecodePayload (virnetmessage.c:286)
==9020==    by 0x4D03235: virNetClientProgramCall (virnetclientprogram.c:318)
==9020==    by 0x4CE7262: call (remote_driver.c:3925)
==9020==    by 0x4CED8D2: remoteNetworkGetBridgeName (remote_client_bodies.h:3384)
==9020==    by 0x4CC494E: virNetworkGetBridgeName (libvirt.c:8503)
==9020==    by 0x40F654: cmdNetworkInfo (virsh.c:5015)
==9020==    by 0x410D02: vshCommandRun (virsh.c:12738)
==9020==    by 0x41F2D5: main (virsh.c:14084)
==9020==
==9020== 10 bytes in 1 blocks are definitely lost in loss record 3 of 26
==9020==    at 0x4A05FDE: malloc (vg_replace_malloc.c:236)
==9020==    by 0x386A27F8A1: strdup (in /lib64/libc-2.12.so)
==9020==    by 0x4CF508B: doRemoteOpen (remote_driver.c:364)
==9020==    by 0x4CF6E8F: remoteOpen (remote_driver.c:800)
==9020==    by 0x4CCB384: do_open (libvirt.c:1054)
==9020==    by 0x4CCBEB5: virConnectOpenAuth (libvirt.c:1280)
==9020==    by 0x410BC0: vshReconnect (virsh.c:589)
==9020==    by 0x410DCF: vshCommandRun (virsh.c:12733)
==9020==    by 0x41F2D5: main (virsh.c:14084)
==9020==
==9020== 56 (24 direct, 32 indirect) bytes in 1 blocks are definitely lost in loss record 17 of 26
==9020==    at 0x4A04A28: calloc (vg_replace_malloc.c:467)
==9020==    by 0x4C686ED: virAlloc (memory.c:101)
==9020==    by 0x4C96870: virDomainEventStateNew (domain_event.c:578)
==9020==    by 0x4CF5A8E: doRemoteOpen (remote_driver.c:658)
==9020==    by 0x4CF6E8F: remoteOpen (remote_driver.c:800)
==9020==    by 0x4CCB384: do_open (libvirt.c:1054)
==9020==    by 0x4CCBEB5: virConnectOpenAuth (libvirt.c:1280)
==9020==    by 0x410BC0: vshReconnect (virsh.c:589)
==9020==    by 0x410DCF: vshCommandRun (virsh.c:12733)
==9020==    by 0x41F2D5: main (virsh.c:14084)

Note: remote memory leak are a known bug: https://bugzilla.redhat.com/show_bug.cgi?id=690734, 
      so this patch only fix network memory leak.

The following codes leads memory leak:
2448 static char *networkGetBridgeName(virNetworkPtr net) {
2449     struct network_driver *driver = net->conn->networkPrivateData;
2450     virNetworkObjPtr network;
2451     char *bridge = NULL;
......
2470     bridge = strdup(network->def->bridge);

Cleanup section hasn't released allocation free, and the programming will return a NULL if only and only 
error condition happen, if everything is okay, 'bridge' will be returned, right?


Regards,
Alex

-- libvir-list mailing list libvir-list redhat com https://www.redhat.com/mailman/listinfo/libvir-list
Yeah, we need to return 'bridge' pointer variable, so shouldn't free it, I should fix other function memory leak.

Thanks,
Alex
Alex

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