Commit e47608ab authored Aug 04, 2016 by zijun_hu Committed by Linus Torvalds Aug 04, 2016

mm/memblock.c: fix NULL dereference error

It causes NULL dereference error and failure to get type_a->regions[0]
info if parameter type_b of __next_mem_range_rev() == NULL

Fix this by checking before dereferring and initializing idx_b to 0

The approach is tested by dumping all types of region via
__memblock_dump_all() and __next_mem_range_rev() fixed to UART
separately the result is okay after checking the logs.

Link: http://lkml.kernel.org/r/57A0320D.6070102@zoho.com


Signed-off-by: zijun_hu <zijun_hu@htc.com>
Tested-by: zijun_hu <zijun_hu@htc.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 4b16b0c0

mm/memblock.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -994,7 +994,10 @@ void __init_memblock __next_mem_range_rev(u64 *idx, int nid, ulong flags,

		if (*idx == (u64)ULLONG_MAX) {
		idx_a = type_a->cnt - 1;
		if (type_b != NULL)
		idx_b = type_b->cnt;
		else
		idx_b = 0;
		}

		for (; idx_a >= 0; idx_a--) {

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