3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yisheng Xie <xieyisheng1@xxxxxxxxxx> [ Upstream commit 8970a63e965b43288c4f5f40efbc2bbf80de7f16 ] 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@xxxxxxxxxxxxxxxxxxxx: slight comment tweak] Link: http://lkml.kernel.org/r/4ebee1c2-57f6-bcb8-0e2d-1833d1ee0bb7@xxxxxxxxxx Fixes: fc36b8d3d819 ("mempolicy: use MPOL_F_LOCAL to Indicate Preferred Local Policy") Signed-off-by: Yisheng Xie <xieyisheng1@xxxxxxxxxx> Reported-by: Alexander Potapenko <glider@xxxxxxxxxx> Tested-by: Alexander Potapenko <glider@xxxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Dmitriy Vyukov <dvyukov@xxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/mempolicy.c | 3 +++ 1 file changed, 3 insertions(+) --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2169,6 +2169,9 @@ bool __mpol_equal(struct mempolicy *a, s 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();
