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SubjectRe: [PATCH v2 2/2] mm: usercopy: Warn vmalloc/module address in check_heap_object()
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Le 25/12/2021 à 13:06, Kefeng Wang a écrit :
> virt_addr_valid() could be insufficient to validate the virt addr
> on some architecture, which could lead to potential BUG which has
> been found on arm64/powerpc64.
>
> Let's add WARN_ON to check if the virt addr is passed virt_addr_valid()
> but is a vmalloc/module address.

I think that's the responsibility of the architecture and doesn't
deserve a WARN_ON() in generic code.

The generic code cannot check all what architectures do wrong.

Eventually you can do some testing at startup, maybe with
CONFIG_DEBUG_VM_PGTABLE, but I don't think we should have such
verification in functions like check_heap_object()

>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
> mm/usercopy.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/mm/usercopy.c b/mm/usercopy.c
> index b3de3c4eefba..ce83e0b137dd 100644
> --- a/mm/usercopy.c
> +++ b/mm/usercopy.c
> @@ -228,6 +228,8 @@ static inline void check_heap_object(const void *ptr, unsigned long n,
> if (!virt_addr_valid(ptr))
> return;
>
> + WARN_ON_ONCE(is_vmalloc_or_module_addr(ptr));
> +
> /*
> * When CONFIG_HIGHMEM=y, kmap_to_page() will give either the
> * highmem page or fallback to virt_to_page(). The following
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