[libvirt] [PATCH] numa: fix unsafe access to numa_nodes_ptr

numa_nodes_ptr is a global variable in libnuma.so. It is been freed after main thread exits. If we have many running vms, restart the libvirtd service continuously at intervals of a few seconds, the main thread may exit before qemuProcessReconnect thread, and a segfault error occurs. Backstrace as follows: 0 0x00007f40e3d2dd72 in numa_bitmask_isbitset () from /lib64/libnuma.so.1 1 0x00007f40e4d14c55 in virNumaNodeIsAvailable (node=node@entry=0) at util/virnuma.c:396 2 0x00007f40e4d16010 in virNumaGetHostMemoryNodeset () at util/virnuma.c:1011 3 0x00007f40b94ced90 in qemuRestoreCgroupState (vm=0x7f407c39df00, vm=0x7f407c39df00) at qemu/qemu_cgroup.c:877 4 qemuConnectCgroup (driver=driver@entry=0x7f407c21fe80, vm=0x7f407c39df00) at qemu/qemu_cgroup.c:969 5 0x00007f40b94eef93 in qemuProcessReconnect (opaque=<optimized out>) at qemu/qemu_process.c:3531 6 0x00007f40e4d34bd2 in virThreadHelper (data=<optimized out>) at util/virthread.c:206 7 0x00007f40e214ee25 in start_thread () from /lib64/libpthread.so.0 8 0x00007f40e1e7c36d in clone () from /lib64/libc.so.6 Signed-off-by: Wang Yechao <wang.yechao255(a)zte.com.cn&gt; --- src/util/virnuma.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/src/util/virnuma.c b/src/util/virnuma.c index 67e6c86..502b1d5 100644 --- a/src/util/virnuma.c +++ b/src/util/virnuma.c @@ -381,7 +381,10 @@ virNumaGetMaxCPUs(void) bool virNumaNodeIsAvailable(int node) { - return numa_bitmask_isbitset(numa_nodes_ptr, node); + if (numa_nodes_ptr) + return numa_bitmask_isbitset(numa_nodes_ptr, node); + else + return false; } -- 1.8.3.1