Commit d6d8c8a4 authored Feb 24, 2017 by zhong jiang Committed by Linus Torvalds Feb 24, 2017

mm/memory_hotplug.c: fix overflow in test_pages_in_a_zone()

When mainline introduced commit a96dfddb ("base/memory, hotplug: fix
a kernel oops in show_valid_zones()"), it obtained the valid start and
end pfn from the given pfn range.  The valid start pfn can fix the
actual issue, but it introduced another issue.  The valid end pfn will
may exceed the given end_pfn.

Although the incorrect overflow will not result in actual problem at
present, but I think it need to be fixed.

[toshi.kani@hpe.com: remove assumption that end_pfn is aligned by MAX_ORDER_NR_PAGES]
Fixes: a96dfddb ("base/memory, hotplug: fix a kernel oops in show_valid_zones()")
Link: http://lkml.kernel.org/r/1486467299-22648-1-git-send-email-zhongjiang@huawei.com


Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 8e19d540

mm/memory_hotplug.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1509,7 +1509,7 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn,
		while ((i < MAX_ORDER_NR_PAGES) &&
		!pfn_valid_within(pfn + i))
		i++;
		if (i == MAX_ORDER_NR_PAGES)
		if (i == MAX_ORDER_NR_PAGES \|\| pfn + i >= end_pfn)
		continue;
		page = pfn_to_page(pfn + i);
		if (zone && page_zone(page) != zone)
		@@ -1523,7 +1523,7 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn,

		if (zone) {
		*valid_start = start;
		*valid_end = end;
		*valid_end = min(end, end_pfn);
		return 1;
		} else {
		return 0;

Admin message