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authorVlastimil Babka <vbabka@suse.cz>2017-01-24 15:18:18 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-02-01 08:30:52 +0100
commitf11e8bf8e99bf3f7364135a0d15549586d6c6933 (patch)
tree16bdf67acedbff77d9c48233b71e1f4c166d9ddc
parentc83ad9703e71720bb5001daab7cbaf9b8d59b084 (diff)
mm/mempolicy.c: do not put mempolicy before using its nodemask
commit d51e9894d27492783fc6d1b489070b4ba66ce969 upstream. Since commit be97a41b291e ("mm/mempolicy.c: merge alloc_hugepage_vma to alloc_pages_vma") alloc_pages_vma() can potentially free a mempolicy by mpol_cond_put() before accessing the embedded nodemask by __alloc_pages_nodemask(). The commit log says it's so "we can use a single exit path within the function" but that's clearly wrong. We can still do that when doing mpol_cond_put() after the allocation attempt. Make sure the mempolicy is not freed prematurely, otherwise __alloc_pages_nodemask() can end up using a bogus nodemask, which could lead e.g. to premature OOM. Fixes: be97a41b291e ("mm/mempolicy.c: merge alloc_hugepage_vma to alloc_pages_vma") Link: http://lkml.kernel.org/r/20170118141124.8345-1-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--mm/mempolicy.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 87a177917cb2..a4217fe60dff 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2006,8 +2006,8 @@ retry_cpuset:
nmask = policy_nodemask(gfp, pol);
zl = policy_zonelist(gfp, pol, node);
- mpol_cond_put(pol);
page = __alloc_pages_nodemask(gfp, order, zl, nmask);
+ mpol_cond_put(pol);
out:
if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
goto retry_cpuset;