On Tue, Jan 28, 2014 at 05:05:16PM +0800, Tang Chen wrote:
> The following path will cause array out of bound.
>
> memblock_add_region() will always set nid in memblock.reserved to
> MAX_NUMNODES.
> In numa_register_memblks(), after we set all nid to correct valus in
> memblock.reserved,
> we called setup_node_data(), and used memblock_alloc_nid() to allocate
> memory, with
> nid set to MAX_NUMNODES.
>
> The nodemask_t type can be seen as a bit array. And the index is 0 ~
> MAX_NUMNODES-1.
>
> After that, when we call node_set() in numa_clear_kernel_node_hotplug(), the
> nodemask_t
> got an index of value MAX_NUMNODES, which is out of [0 ~ MAX_NUMNODES-1].
>
> See below:
>
> numa_init()
> |---> numa_register_memblks()
> | |---> memblock_set_node(memory) set correct nid in
> memblock.memory
> | |---> memblock_set_node(reserved) set correct nid in
> memblock.reserved
> | |......
> | |---> setup_node_data()
> | |---> memblock_alloc_nid() here, nid is set to
> MAX_NUMNODES (1024)
> |......
> |---> numa_clear_kernel_node_hotplug()
> |---> node_set() here, we have an index 1024,
> and overflowed
>
> This patch moves nid setting to numa_clear_kernel_node_hotplug() to fix this
> problem.
>
> Reported-by: Dave Jones <da...@redhat.com>
> Signed-off-by: Tang Chen <tangc...@cn.fujitsu.com>
> Tested-by: Gu Zheng <guz.f...@cn.fujitsu.com>
> ---
> arch/x86/mm/numa.c | 19 +++++++++++--------
> 1 file changed, 11 insertions(+), 8 deletions(-)
This does seem to solve the problem (In conjunction with David's variant of the
other patch).
Dave
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