From 54df8e39ce257bc668427dc3bac6e1625e2e7c96 Mon Sep 17 00:00:00 2001
From: Muchun Song <songmuchun@bytedance.com>
Date: Thu, 23 Mar 2023 10:50:03 +0800
Subject: [PATCH] mm: kfence: fix handling discontiguous page
commit 1f2803b2660f4b04d48d065072c0ae0c9ca255fd 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: 0ce20dd84089 ("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>
---
mm/kfence/core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index 5e4c1abc794f8..a477b7fb8aa33 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -557,7 +557,7 @@ 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;
@@ -603,7 +603,7 @@ 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;
--
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