Commit 8970a63e authored Mar 22, 2018 by Yisheng Xie Committed by Linus Torvalds Mar 22, 2018

mm/mempolicy.c: avoid use uninitialized preferred_node

Alexander reported a use of uninitialized memory in __mpol_equal(),
which is caused by incorrect use of preferred_node.

When mempolicy in mode MPOL_PREFERRED with flags MPOL_F_LOCAL, it uses
numa_node_id() instead of preferred_node, however, __mpol_equal() uses
preferred_node without checking whether it is MPOL_F_LOCAL or not.

[akpm@linux-foundation.org: slight comment tweak]
Link: http://lkml.kernel.org/r/4ebee1c2-57f6-bcb8-0e2d-1833d1ee0bb7@huawei.com


Fixes: fc36b8d3 ("mempolicy: use MPOL_F_LOCAL to Indicate Preferred Local Policy")
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Reported-by: Alexander Potapenko <glider@google.com>
Tested-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 3215b9d5

mm/mempolicy.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -2124,6 +2124,9 @@ bool __mpol_equal(struct mempolicy a, struct mempolicy b)
		case MPOL_INTERLEAVE:
		return !!nodes_equal(a->v.nodes, b->v.nodes);
		case MPOL_PREFERRED:
		/* a's ->flags is the same as b's */
		if (a->flags & MPOL_F_LOCAL)
		return true;
		return a->v.preferred_node == b->v.preferred_node;
		default:
		BUG();

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