On Fri, Mar 9, 2018 at 6:21 AM, Yisheng Xie <xieyisheng1@xxxxxxxxxx> wrote: > 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@xxxxxxxxxx> > Signed-off-by: Yisheng Xie <xieyisheng1@xxxxxxxxxx> Tested-by: Alexander Potapenko <glider@xxxxxxxxxx> I confirm that the patch fixes the problem. Thanks for the quick turnaround! Any idea which commit had introduced the bug in the first place? > --- > 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 > -- Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Straße, 33 80636 München Geschäftsführer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg
