* [PATCH] mm: kfence: fix handling discontiguous page
@ 2023-03-23 2:50 Muchun Song
2023-03-23 8:28 ` Marco Elver
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Muchun Song @ 2023-03-23 2:50 UTC (permalink / raw)
To: glider, elver, dvyukov, akpm, jannh, sjpark, muchun.song
Cc: kasan-dev, linux-mm, linux-kernel, Muchun Song
The struct pages could be discontiguous when the kfence pool is allocated
via alloc_contig_pages() with CONFIG_SPARSEMEM and !CONFIG_SPARSEMEM_VMEMMAP.
So, the iteration should use nth_page().
Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
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 d66092dd187c..1065e0568d05 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -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;
--
2.11.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] mm: kfence: fix handling discontiguous page
2023-03-23 2:50 [PATCH] mm: kfence: fix handling discontiguous page Muchun Song
@ 2023-03-23 8:28 ` Marco Elver
2023-03-23 22:18 ` Andrew Morton
2023-03-24 3:43 ` Kefeng Wang
2 siblings, 0 replies; 5+ messages in thread
From: Marco Elver @ 2023-03-23 8:28 UTC (permalink / raw)
To: Muchun Song
Cc: glider, dvyukov, akpm, jannh, sjpark, muchun.song, kasan-dev,
linux-mm, linux-kernel
On Thu, 23 Mar 2023 at 03:50, 'Muchun Song' via kasan-dev
<kasan-dev@googlegroups.com> wrote:
>
> The struct pages could be discontiguous when the kfence pool is allocated
> via alloc_contig_pages() with CONFIG_SPARSEMEM and !CONFIG_SPARSEMEM_VMEMMAP.
> So, the iteration should use nth_page().
>
> Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Marco Elver <elver@google.com>
> ---
> 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 d66092dd187c..1065e0568d05 100644
> --- a/mm/kfence/core.c
> +++ b/mm/kfence/core.c
> @@ -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;
> --
> 2.11.0
>
> --
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^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] mm: kfence: fix handling discontiguous page
2023-03-23 2:50 [PATCH] mm: kfence: fix handling discontiguous page Muchun Song
2023-03-23 8:28 ` Marco Elver
@ 2023-03-23 22:18 ` Andrew Morton
2023-03-24 1:59 ` Muchun Song
2023-03-24 3:43 ` Kefeng Wang
2 siblings, 1 reply; 5+ messages in thread
From: Andrew Morton @ 2023-03-23 22:18 UTC (permalink / raw)
To: Muchun Song
Cc: glider, elver, dvyukov, jannh, sjpark, muchun.song, kasan-dev,
linux-mm, linux-kernel
On Thu, 23 Mar 2023 10:50:03 +0800 Muchun Song <songmuchun@bytedance.com> wrote:
> The struct pages could be discontiguous when the kfence pool is allocated
> via alloc_contig_pages() with CONFIG_SPARSEMEM and !CONFIG_SPARSEMEM_VMEMMAP.
> So, the iteration should use nth_page().
What are the user-visible runtime effects of this flaw?
Thanks.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: kfence: fix handling discontiguous page
2023-03-23 22:18 ` Andrew Morton
@ 2023-03-24 1:59 ` Muchun Song
0 siblings, 0 replies; 5+ messages in thread
From: Muchun Song @ 2023-03-24 1:59 UTC (permalink / raw)
To: Andrew Morton
Cc: Muchun Song, glider, elver, dvyukov, jannh, sjpark, kasan-dev,
Linux Memory Management List, linux-kernel
> On Mar 24, 2023, at 06:18, Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Thu, 23 Mar 2023 10:50:03 +0800 Muchun Song <songmuchun@bytedance.com> wrote:
>
>> The struct pages could be discontiguous when the kfence pool is allocated
>> via alloc_contig_pages() with CONFIG_SPARSEMEM and !CONFIG_SPARSEMEM_VMEMMAP.
>> So, the iteration should use nth_page().
>
> What are the user-visible runtime effects of this flaw?
Set the PG_slab and memcg_data to a arbitrary address (may be not used as a struct
page), so the worst case may corrupt the kernel.
Thanks.
>
> Thanks.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: kfence: fix handling discontiguous page
2023-03-23 2:50 [PATCH] mm: kfence: fix handling discontiguous page Muchun Song
2023-03-23 8:28 ` Marco Elver
2023-03-23 22:18 ` Andrew Morton
@ 2023-03-24 3:43 ` Kefeng Wang
2 siblings, 0 replies; 5+ messages in thread
From: Kefeng Wang @ 2023-03-24 3:43 UTC (permalink / raw)
To: Muchun Song, glider, elver, dvyukov, akpm, jannh, sjpark, muchun.song
Cc: kasan-dev, linux-mm, linux-kernel
On 2023/3/23 10:50, Muchun Song wrote:
> The struct pages could be discontiguous when the kfence pool is allocated
> via alloc_contig_pages() with CONFIG_SPARSEMEM and !CONFIG_SPARSEMEM_VMEMMAP.
> So, the iteration should use nth_page().
>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> ---
> 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 d66092dd187c..1065e0568d05 100644
> --- a/mm/kfence/core.c
> +++ b/mm/kfence/core.c
> @@ -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;
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2023-03-24 3:44 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2023-03-23 2:50 [PATCH] mm: kfence: fix handling discontiguous page Muchun Song
2023-03-23 8:28 ` Marco Elver
2023-03-23 22:18 ` Andrew Morton
2023-03-24 1:59 ` Muchun Song
2023-03-24 3:43 ` Kefeng Wang
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