Re: [libvirt] [PATCH] network: plug unininitialized read found by valgrind

* src/util/network.c (virSocketAddrMask): Zero out port, so that iptables can initialize just the netmask, then call virSocketFormatAddr without an uninitialized read in getnameinfo. --- I'm not sure if this is the best patch; an alternative would be to call memset(network,0,sizeof network) in iptablesFormatNetwork prior to virSocketAddrMaskByPrefix. But with this patch in place, valgrind no longer complained about: ==31478== Use of uninitialised value of size 8 ==31478== at 0x3021643DAB: _itoa_word (in /lib64/libc-2.12.so) ==31478== by 0x3021644E74: vfprintf (in /lib64/libc-2.12.so) ==31478== by 0x302166EFB1: vsnprintf (in /lib64/libc-2.12.so) ==31478== by 0x302164F022: snprintf (in /lib64/libc-2.12.so) ==31478== by 0x3021705135: getnameinfo (in /lib64/libc-2.12.so) ==31478== by 0x4E4FE00: virSocketFormatAddrFull (network.c:194) ==31478== by 0x4E4FCAE: virSocketFormatAddr (network.c:152) ==31478== by 0x4E43688: iptablesFormatNetwork (iptables.c:307) ==31478== by 0x4E43FDE: iptablesForwardMasquerade (iptables.c:761) ==31478== by 0x4E44392: iptablesRemoveForwardMasquerade (iptables.c:863) ==31478== by 0x4A8BEF: networkRemoveMasqueradingIptablesRules (bridge_driver.c:893) ==31478== by 0x4A9BCA: networkRemoveIpSpecificIptablesRules (bridge_driver.c:1244) ==31478== Uninitialised value was created by a stack allocation ==31478== at 0x4E43570: iptablesFormatNetwork (iptables.c:289) So I'm assuming that the uninitialized read was due to gethostname looking at the port field which was still filled with uninitialized stack data. src/util/network.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) diff --git a/src/util/network.c b/src/util/network.c index a7e7423..33028aa 100644 --- a/src/util/network.c +++ b/src/util/network.c @@ -1,7 +1,7 @@ /* * network.c: network helper APIs for libvirt * - * Copyright (C) 2009-2010 Red Hat, Inc. + * Copyright (C) 2009-2011 Red Hat, Inc. * * See COPYING.LIB for the License of this software * @@ -291,6 +291,7 @@ int virSocketAddrIsNetmask(virSocketAddrPtr netmask) { * virSocketAddrMask: * @addr: address that needs to be masked * @netmask: the netmask address + * @network: where to store the result, can be same as @addr * * Mask off the host bits of @addr according to @netmask, turning it * into a network address. @@ -311,6 +312,7 @@ virSocketAddrMask(const virSocketAddrPtr addr, network->data.inet4.sin_addr.s_addr = (addr->data.inet4.sin_addr.s_addr & netmask->data.inet4.sin_addr.s_addr); + network->data.inet4.sin_port = 0; network->data.stor.ss_family = AF_INET; network->len = addr->len; return 0; @@ -322,6 +324,7 @@ virSocketAddrMask(const virSocketAddrPtr addr, = (addr->data.inet6.sin6_addr.s6_addr[ii] & netmask->data.inet6.sin6_addr.s6_addr[ii]); } + network->data.inet6.sin6_port = 0; network->data.stor.ss_family = AF_INET6; network->len = addr->len; return 0; @@ -334,6 +337,7 @@ virSocketAddrMask(const virSocketAddrPtr addr, * virSocketAddrMaskByPrefix: * @addr: address that needs to be masked * @prefix: prefix (# of 1 bits) of netmask to apply + * @network: where to store the result, can be same as @addr * * Mask off the host bits of @addr according to @prefix, turning it * into a network address.