2019-09-16 08:58:59

by Alastair D'Silva

Subject: [PATCH v2 2/2] mm: Add a bounds check in devm_memremap_pages()

From: Alastair D'Silva <[email protected]>

The call to check_hotplug_memory_addressable() validates that the memory
is fully addressable.

Without this call, it is possible that we may remap pages that is
not physically addressable, resulting in bogus section numbers
being returned from __section_nr().

Signed-off-by: Alastair D'Silva <[email protected]>
---
mm/memremap.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/mm/memremap.c b/mm/memremap.c
index 86432650f829..fd00993caa3e 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -269,6 +269,13 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)

mem_hotplug_begin();

+ error = check_hotplug_memory_addressable(res->start,
+ resource_size(res));
+ if (error) {
+ mem_hotplug_done();
+ goto err_checkrange;
+ }
+
/*
* For device private memory we call add_pages() as we only need to
* allocate and initialize struct page for the device memory. More-
@@ -324,6 +331,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)

err_add_memory:
kasan_remove_zero_shadow(__va(res->start), resource_size(res));
+ err_checkrange:
err_kasan:
untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
err_pfn_remap:
--
2.21.0

2019-09-16 10:41:10

by David Hildenbrand

Subject: Re: [PATCH v2 2/2] mm: Add a bounds check in devm_memremap_pages()

On 16.09.19 08:05, Alastair D'Silva wrote:
> From: Alastair D'Silva <[email protected]>
>
> The call to check_hotplug_memory_addressable() validates that the memory
> is fully addressable.
>
> Without this call, it is possible that we may remap pages that is
> not physically addressable, resulting in bogus section numbers
> being returned from __section_nr().
>
> Signed-off-by: Alastair D'Silva <[email protected]>
> ---
> mm/memremap.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/mm/memremap.c b/mm/memremap.c
> index 86432650f829..fd00993caa3e 100644
> --- a/mm/memremap.c
> +++ b/mm/memremap.c
> @@ -269,6 +269,13 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
>
> mem_hotplug_begin();
>
> + error = check_hotplug_memory_addressable(res->start,
> + resource_size(res));
> + if (error) {
> + mem_hotplug_done();
> + goto err_checkrange;
> + }

As I said in reply to v1, please move this out of the memory hotplug
lock. These are static checks.

> +
> /*
> * For device private memory we call add_pages() as we only need to
> * allocate and initialize struct page for the device memory. More-
> @@ -324,6 +331,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
>
> err_add_memory:
> kasan_remove_zero_shadow(__va(res->start), resource_size(res));
> + err_checkrange:
> err_kasan:
> untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
> err_pfn_remap:
>


--

Thanks,

David / dhildenb