On 08/02/2016 01:03 PM, zijun_hu wrote: > Hi Andrew, > > this patch is part of https://lkml.org/lkml/2016/7/26/347 and isn't merged in > as you advised in another mail, i release this patch against linus's mainline > for fixing relevant bugs completely, see test patch attached for verification > details > >>From 5a74cb46b7754a45428ff95f4653ad27025c3131 Mon Sep 17 00:00:00 2001 > From: zijun_hu <zijun_hu@xxxxxxx> > Date: Tue, 2 Aug 2016 12:35:28 +0800 > Subject: [PATCH] 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 > > the bugs are fixed 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 > > Signed-off-by: zijun_hu <zijun_hu@xxxxxxx> > Tested-by: zijun_hu <zijun_hu@xxxxxxx> > Acked-by: Tejun Heo <tj@xxxxxxxxxx> > --- > mm/memblock.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index ff5ff3b..250dd48 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -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--) { > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>