When passing the return value of dev_to_node() to cpumask_of_node() without checking the node id if the node id is NUMA_NO_NODE, there is global-out-of-bounds detected by KASAN. >From the discussion [1], NUMA_NO_NODE really means no node affinity, which also means all cpus should be usable. So the cpumask_of_node() should always return all cpus online when user passes the node id as NUMA_NO_NODE, just like similar semantic that page allocator handles NUMA_NO_NODE. But we cannot really copy the page allocator logic. Simply because the page allocator doesn't enforce the near node affinity. It just picks it up as a preferred node but then it is free to fallback to any other numa node. This is not the case here and node_to_cpumask_map will only restrict to the particular node's cpus which would have really non deterministic behavior depending on where the code is executed. So in fact we really want to return cpu_online_mask for NUMA_NO_NODE. Since this arch was already NUMA_NO_NODE aware, this patch only changes it to return cpu_online_mask. [1] https://lore.kernel.org/patchwork/patch/1125789/ Signed-off-by: Yunsheng Lin <linyunsheng@xxxxxxxxxx> Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx> --- V3: Change to only handle NUMA_NO_NODE, and return cpu_online_mask for NUMA_NO_NODE case, and change the commit log to better justify the change. --- arch/alpha/include/asm/topology.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/alpha/include/asm/topology.h b/arch/alpha/include/asm/topology.h index 5a77a40..836c9e2 100644 --- a/arch/alpha/include/asm/topology.h +++ b/arch/alpha/include/asm/topology.h @@ -31,7 +31,7 @@ static const struct cpumask *cpumask_of_node(int node) int cpu; if (node == NUMA_NO_NODE) - return cpu_all_mask; + return cpu_online_mask; cpumask_clear(&node_to_cpumask_map[node]); -- 2.8.1
