arch/x86/mm/numa.c: fix array index overflow when synchronizing nid to memblock.reserved.

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>
Reported-by: Dave Jones <davej@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Tested-by: Dave Jones <davej@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 8 deletions

diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 45ec9d72b6dd..27aa0455fab3 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);
         }
 
         /*
@@ -569,6 +561,17 @@ static void __init numa_clear_kernel_node_hotplug(void)
         unsigned long start, end;
         struct memblock_type *type = &memblock.reserved;
 
+        /*
+         * 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);