Commit 7bc35fdd authored Feb 06, 2014 by Tang Chen Committed by Linus Torvalds Feb 06, 2014

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>

parent 017c217a

arch/x86/mm/numa.c

+11 −8

Original line number	Diff line number	Diff line
		@@ -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);

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