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

When mainline introduced commit a96dfddbcc ("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: a96dfddbcc ("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>
This commit is contained in:
zhong jiang 2017-02-24 14:59:30 -08:00 committed by Linus Torvalds
parent 8e19d540d1
commit d6d8c8a482
1 changed files with 2 additions and 2 deletions
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4
mm/memory_hotplug.c
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@ -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;