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Eric Blake
b9dacdd4d9
daemon: avoid memleak when ListAll returns nothing
Commit 4f25146 (v1.2.8) managed to silence Coverity, but at the cost of a memory leak detected by valgrind: ==24129== 40 bytes in 5 blocks are definitely lost in loss record 355 of 637 ==24129== at 0x4A08B1C: realloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so) ==24129== by 0x5084B8E: virReallocN (viralloc.c:245) ==24129== by 0x514D5AA: virDomainObjListExport (domain_conf.c:22200) ==24129== by 0x201227DB: qemuConnectListAllDomains (qemu_driver.c:18042) ==24129== by 0x51CC1B6: virConnectListAllDomains (libvirt-domain.c:6797) ==24129== by 0x14173D: remoteDispatchConnectListAllDomains (remote.c:1580) ==24129== by 0x121BE1: remoteDispatchConnectListAllDomainsHelper (remote_dispatch.h:1072) In short, every time a client calls a ListAll variant and asks for the resulting list, but there are 0 elements to return, we end up leaking the 1-entry array that holds the NULL terminator. What's worse, a read-only client can access these functions in a tight loop to cause libvirtd to eventually run out of memory; and this can be considered a denial of service attack against more privileged clients. Thankfully, the leak is so small (8 bytes per call) that you would already have some other denial of service with any guest calling the API that frequently, so an out-of-memory crash is unlikely enough that this did not warrant a CVE. * daemon/remote.c (remoteDispatchConnectListAllDomains) (remoteDispatchDomainListAllSnapshots) (remoteDispatchDomainSnapshotListAllChildren) (remoteDispatchConnectListAllStoragePools) (remoteDispatchStoragePoolListAllVolumes) (remoteDispatchConnectListAllNetworks) (remoteDispatchConnectListAllInterfaces) (remoteDispatchConnectListAllNodeDevices) (remoteDispatchConnectListAllNWFilters) (remoteDispatchConnectListAllSecrets) (remoteDispatchNetworkGetDHCPLeases): Plug leak. Signed-off-by: Eric Blake <eblake@redhat.com> (cherry picked from commit 3c2ff5029b83c9b33be0f1607a3c61f4f5850612) Signed-off-by: Eric Blake <eblake@redhat.com> Conflicts: daemon/remote.c - context with older cleanup styles
LibVirt : simple API for virtualization Libvirt is a C toolkit to interact with the virtualization capabilities of recent versions of Linux (and other OSes). It is free software available under the GNU Lesser General Public License. Virtualization of the Linux Operating System means the ability to run multiple instances of Operating Systems concurrently on a single hardware system where the basic resources are driven by a Linux instance. The library aim at providing long term stable C API initially for the Xen paravirtualization but should be able to integrate other virtualization mechanisms if needed. Daniel Veillard <veillard@redhat.com>
Description
Libvirt provides a portable, long term stable C API for managing the
virtualization technologies provided by many operating systems. It
includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware
vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER
Hypervisor.
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