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Subject[PATCH 2/2] numa, mem-hotplug: Fix array index overflow when synchronizing nid to memblock.reserved.
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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 <davej@redhat.com>
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Tested-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
---
arch/x86/mm/numa.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 00c9f09..a183b43 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -493,14 +493,6 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
struct numa_memblk *mb = &mi->blk[i];
memblock_set_node(mb->start, mb->end - mb->start,
&memblock.memory, mb->nid);
-
- /*
- * At this time, all memory regions reserved by memblock are
- * used by the kernel. Set the nid in memblock.reserved will
- * mark out all the nodes the kernel resides in.
- */
- memblock_set_node(mb->start, mb->end - mb->start,
- &memblock.reserved, mb->nid);
}

/*
@@ -571,6 +563,17 @@ static void __init numa_clear_kernel_node_hotplug(void)

nodes_clear(numa_kernel_nodes);

+ /*
+ * At this time, all memory regions reserved by memblock are
+ * used by the kernel. Set the nid in memblock.reserved will
+ * mark out all the nodes the kernel resides in.
+ */
+ for (i = 0; i < numa_meminfo.nr_blks; i++) {
+ struct numa_memblk *mb = &numa_meminfo.blk[i];
+ memblock_set_node(mb->start, mb->end - mb->start,
+ &memblock.reserved, mb->nid);
+ }
+
/* Mark all kernel nodes. */
for (i = 0; i < type->cnt; i++)
node_set(type->regions[i].nid, numa_kernel_nodes);
--
1.8.3.1



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