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authorVlastimil Babka <vbabka@suse.cz>2017-01-24 23:18:18 (GMT)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-02-01 07:33:04 (GMT)
commit9b1a1ae9b5281e12893a34bcbd1686b5bcd2cd82 (patch)
treeeeb0e09321d045b46c66a1ba5a684b4d2072154e /mm/mempolicy.c
parent6676aa65464f23e32efe1857a51fe341dfb10e03 (diff)
downloadlinux-9b1a1ae9b5281e12893a34bcbd1686b5bcd2cd82.tar.xz
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>
Diffstat (limited to 'mm/mempolicy.c')
-rw-r--r--mm/mempolicy.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 0b859af..f757047 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2023,8 +2023,8 @@ 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;