On 2021/12/27 1:33, Christophe Leroy wrote:
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()
Ok, we could find other better place to add a virt_to_valid() check
instead of this one.
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
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
