The patch titled
Subject: mm/hugetlb: fix use after free when subpool max_hpages accounting is not enabled
has been added to the -mm tree. Its filename is
mm-hugetlb-fix-use-after-free-when-subpool-max_hpages-accounting-is-not-enabled.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-fix-use-after-free-when-subpool-max_hpages-accounting-is-not-enabled.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-fix-use-after-free-when-subpool-max_hpages-accounting-is-not-enabled.patch
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------------------------------------------------------
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm/hugetlb: fix use after free when subpool max_hpages accounting is not enabled
When subpool max_hpages accounting is not enabled, used_hpages is always 0
and might lead to release subpool prematurely because it indicates no
pages are used now while there might be.
In order to fix this issue, we should check used_hpages == 0 iff
max_hpages accounting is enabled. As max_hpages accounting should be
enabled in most common case, this is not worth a Cc stable.
Link: https://lkml.kernel.org/r/20210126115510.53374-1-linmiaohe@xxxxxxxxxx
Signed-off-by: Hongxiang Lou <louhongxiang@xxxxxxxxxx>
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
--- a/mm/hugetlb.c~mm-hugetlb-fix-use-after-free-when-subpool-max_hpages-accounting-is-not-enabled
+++ a/mm/hugetlb.c
@@ -97,16 +97,26 @@ static inline void ClearPageHugeFreed(st
/* Forward declaration */
static int hugetlb_acct_memory(struct hstate *h, long delta);
-static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
+static inline bool subpool_is_free(struct hugepage_subpool *spool)
{
- bool free = (spool->count == 0) && (spool->used_hpages == 0);
+ if (spool->count)
+ return false;
+ if (spool->max_hpages != -1)
+ return spool->used_hpages == 0;
+ if (spool->min_hpages != -1)
+ return spool->rsv_hpages == spool->min_hpages;
+
+ return true;
+}
+static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
+{
spin_unlock(&spool->lock);
/* If no pages are used, and no other handles to the subpool
* remain, give up any reservations based on minimum size and
* free the subpool */
- if (free) {
+ if (subpool_is_free(spool)) {
if (spool->min_hpages != -1)
hugetlb_acct_memory(spool->hstate,
-spool->min_hpages);
_
Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are
mm-page_owner-use-helper-function-zone_end_pfn-to-get-end_pfn.patch
mm-fix-potential-pte_unmap_unlock-pte-error.patch
mm-hugetlb-fix-potential-double-free-in-hugetlb_register_node-error-path.patch
mm-hugetlb-avoid-unnecessary-hugetlb_acct_memory-call.patch
mm-hugetlb-use-helper-huge_page_order-and-pages_per_huge_page.patch
mm-hugetlb-fix-use-after-free-when-subpool-max_hpages-accounting-is-not-enabled.patch
mm-workingsetc-avoid-unnecessary-max_nodes-estimation-in-count_shadow_nodes.patch
z3fold-remove-unused-attribute-for-release_z3fold_page.patch
z3fold-simplify-the-zhdr-initialization-code-in-init_z3fold_page.patch
mm-compaction-remove-duplicated-vm_bug_on_page-pagelocked.patch
hugetlbfs-remove-useless-bug_oninode-in-hugetlbfs_setattr.patch
hugetlbfs-use-helper-macro-default_hstate-in-init_hugetlbfs_fs.patch
hugetlbfs-correct-obsolete-function-name-in-hugetlbfs_read_iter.patch
hugetlbfs-remove-meaningless-variable-avoid_reserve.patch
hugetlbfs-make-hugepage-size-conversion-more-readable.patch
mm-rmap-correct-some-obsolete-comments-of-anon_vma.patch
mm-zsmallocc-convert-to-use-kmem_cache_zalloc-in-cache_alloc_zspage.patch
