--- /dev/null
+From 091d0d55b286c9340201b4ed4470be87fc568228 Mon Sep 17 00:00:00 2001
+From: Li Zefan <lizefan@huawei.com>
+Date: Thu, 9 May 2013 15:08:15 +0800
+Subject: shm: fix null pointer deref when userspace specifies invalid hugepage size
+
+From: Li Zefan <lizefan@huawei.com>
+
+commit 091d0d55b286c9340201b4ed4470be87fc568228 upstream.
+
+Dave reported an oops triggered by trinity:
+
+ BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
+ IP: newseg+0x10d/0x390
+ PGD cf8c1067 PUD cf8c2067 PMD 0
+ Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
+ CPU: 2 PID: 7636 Comm: trinity-child2 Not tainted 3.9.0+#67
+ ...
+ Call Trace:
+ ipcget+0x182/0x380
+ SyS_shmget+0x5a/0x60
+ tracesys+0xdd/0xe2
+
+This bug was introduced by commit af73e4d9506d ("hugetlbfs: fix mmap
+failure in unaligned size request").
+
+Reported-by: Dave Jones <davej@redhat.com>
+Signed-off-by: Li Zefan <lizfan@huawei.com>
+Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
+Acked-by: Rik van Riel <riel@redhat.com>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ ipc/shm.c | 8 +++++++-
+ mm/mmap.c | 8 ++++++--
+ 2 files changed, 13 insertions(+), 3 deletions(-)
+
+--- a/ipc/shm.c
++++ b/ipc/shm.c
+@@ -493,7 +493,13 @@ static int newseg(struct ipc_namespace *
+ if (shmflg & SHM_HUGETLB) {
+ struct hstate *hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT)
+ & SHM_HUGE_MASK);
+- size_t hugesize = ALIGN(size, huge_page_size(hs));
++ size_t hugesize;
++
++ if (!hs) {
++ error = -EINVAL;
++ goto no_file;
++ }
++ hugesize = ALIGN(size, huge_page_size(hs));
+
+ /* hugetlb_file_setup applies strict accounting */
+ if (shmflg & SHM_NORESERVE)
+--- a/mm/mmap.c
++++ b/mm/mmap.c
+@@ -1331,9 +1331,13 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned lon
+ len = ALIGN(len, huge_page_size(hstate_file(file)));
+ } else if (flags & MAP_HUGETLB) {
+ struct user_struct *user = NULL;
++ struct hstate *hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) &
++ SHM_HUGE_MASK);
+
+- len = ALIGN(len, huge_page_size(hstate_sizelog(
+- (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK)));
++ if (!hs)
++ return -EINVAL;
++
++ len = ALIGN(len, huge_page_size(hs));
+ /*
+ * VM_NORESERVE is used because the reservations will be
+ * taken when vm_ops->mmap() is called