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SubjectRe: [PATCH] arm64: numa: check the node id before accessing node_to_cpumask_map
On Fri 30-08-19 10:26:31, Yunsheng Lin wrote:
> Some buggy bios may not set the device' numa id, and dev_to_node
> will return -1, which may cause global-out-of-bounds error
> detected by KASAN.

Why should we workaround a buggy bios like that? Is it so widespread and
no BIOS update available? Also, why is this arm64 specific?

> This patch changes cpumask_of_node to return cpu_none_mask if the
> node is not valid, and sync the cpumask_of_node between the
> cpumask_of_node function in numa.h and numa.c.

Why?

> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
> ---
> arch/arm64/include/asm/numa.h | 6 ++++++
> arch/arm64/mm/numa.c | 2 +-
> 2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/numa.h b/arch/arm64/include/asm/numa.h
> index 626ad01..da891ed 100644
> --- a/arch/arm64/include/asm/numa.h
> +++ b/arch/arm64/include/asm/numa.h
> @@ -25,6 +25,12 @@ const struct cpumask *cpumask_of_node(int node);
> /* Returns a pointer to the cpumask of CPUs on Node 'node'. */
> static inline const struct cpumask *cpumask_of_node(int node)
> {
> + if (node >= nr_node_ids || node < 0)
> + return cpu_none_mask;
> +
> + if (!node_to_cpumask_map[node])
> + return cpu_online_mask;
> +
> return node_to_cpumask_map[node];
> }
> #endif
> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
> index 4f241cc..3846313 100644
> --- a/arch/arm64/mm/numa.c
> +++ b/arch/arm64/mm/numa.c
> @@ -46,7 +46,7 @@ EXPORT_SYMBOL(node_to_cpumask_map);
> */
> const struct cpumask *cpumask_of_node(int node)
> {
> - if (WARN_ON(node >= nr_node_ids))
> + if (WARN_ON(node >= nr_node_ids || node < 0))
> return cpu_none_mask;
>
> if (WARN_ON(node_to_cpumask_map[node] == NULL))
> --
> 2.8.1

--
Michal Hocko
SUSE Labs

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