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mm/memblock.c: fix NULL dereference error

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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>
This commit is contained in:
zijun_hu 2016-08-04 15:32:00 -07:00 committed by Linus Torvalds
parent 4b16b0c0bf
commit e47608ab6d
1 changed files with 4 additions and 1 deletions
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5
mm/memblock.c
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@ -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;
idx_b = type_b->cnt;
if (type_b != NULL)
idx_b = type_b->cnt;
else
idx_b = 0;
}
for (; idx_a >= 0; idx_a--) {