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Subject[PATCH] mm/mempolicy: Avoid use uninitialized preferred_node
Date
Alexander reported an 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 use
numa_node_id() instead of preferred_node, however, __mpol_equeue() use
preferred_node without check whether it is MPOL_F_LOCAL or not.

Reported-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
---
mm/mempolicy.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index d879f1d..641545e 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -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();
--
1.8.3.1
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