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mm: kfence: fix handling discontiguous page 

commit 1f2803b266 upstream.

The struct pages could be discontiguous when the kfence pool is allocated
via alloc_contig_pages() with CONFIG_SPARSEMEM and
!CONFIG_SPARSEMEM_VMEMMAP.

This may result in setting PG_slab and memcg_data to a arbitrary
address (may be not used as a struct page), which in the worst case
might corrupt the kernel.

So the iteration should use nth_page().

Link: https://lkml.kernel.org/r/20230323025003.94447-1-songmuchun@bytedance.com
Fixes: 0ce20dd840 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: SeongJae Park <sjpark@amazon.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Muchun Song 2023-03-23 10:50:03 +08:00 committed by Greg Kroah-Hartman
parent 0aed61c4cf
commit 5e102d209f
1 changed files with 2 additions and 2 deletions
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4
mm/kfence/core.c
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@ -556,7 +556,7 @@ static unsigned long kfence_init_pool(void)
* enters __slab_free() slow-path.
*/
for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) {
struct slab *slab = page_slab(&pages[i]);
struct slab *slab = page_slab(nth_page(pages, i));
if (!i || (i % 2))
continue;
@ -602,7 +602,7 @@ static unsigned long kfence_init_pool(void)
reset_slab:
for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) {
struct slab *slab = page_slab(&pages[i]);
struct slab *slab = page_slab(nth_page(pages, i));
if (!i || (i % 2))
continue;