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| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2017-11-29 16:11:30 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-29 18:40:43 -0800 |
| commit | f4f0a3d85b50a65a348e2b8635041d6b30f01deb (patch) | |
| tree | 11b100039752f93f1ca110a7c8f02cae39448f7a | |
| parent | 5d38f049cee1e1c4a7ac55aa79d37d01ddcc3860 (diff) | |
| download | linux-f4f0a3d85b50a65a348e2b8635041d6b30f01deb.tar.bz2 | |
mm/hugetlb: fix NULL-pointer dereference on 5-level paging machine
I made a mistake during converting hugetlb code to 5-level paging: in
huge_pte_alloc() we have to use p4d_alloc(), not p4d_offset().
Otherwise it leads to crash -- NULL-pointer dereference in pud_alloc()
if p4d table is not yet allocated.
It only can happen in 5-level paging mode. In 4-level paging mode
p4d_offset() always returns pgd, so we are fine.
Link: http://lkml.kernel.org/r/20171122121921.64822-1-kirill.shutemov@linux.intel.com
Fixes: c2febafc6773 ("mm: convert generic code to 5-level paging")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org> [4.11+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/hugetlb.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 698e8fb34031..9a334f5fb730 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4635,7 +4635,9 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, pte_t *pte = NULL; pgd = pgd_offset(mm, addr); - p4d = p4d_offset(pgd, addr); + p4d = p4d_alloc(mm, pgd, addr); + if (!p4d) + return NULL; pud = pud_alloc(mm, p4d, addr); if (pud) { if (sz == PUD_SIZE) { |