| Message ID | 20220412072552.2526871-3-tongtiangen@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: add machine check safe support | expand |
On 2022/4/12 15:25, Tong Tiangen wrote: > In copy_highpage() the `kto` and `kfrom` local variables are pointers to > struct page, but these are used to hold arbitrary pointers to kernel memory > . Each call to page_address() returns a void pointer to memory associated > with the relevant page, and copy_page() expects void pointers to this > memory. > > This inconsistency was introduced in commit 2563776b41c3 ("arm64: mte: > Tags-aware copy_{user_,}highpage() implementations") and while this > doesn't appear to be harmful in practice it is clearly wrong. > > Correct this by making `kto` and `kfrom` void pointers. Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> > Fixes: 2563776b41c3 ("arm64: mte: Tags-aware copy_{user_,}highpage() implementations") > Signed-off-by: Tong Tiangen <tongtiangen@huawei.com> > Acked-by: Mark Rutland <mark.rutland@arm.com> > --- > arch/arm64/mm/copypage.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/mm/copypage.c b/arch/arm64/mm/copypage.c > index b5447e53cd73..0dea80bf6de4 100644 > --- a/arch/arm64/mm/copypage.c > +++ b/arch/arm64/mm/copypage.c > @@ -16,8 +16,8 @@ > > void copy_highpage(struct page *to, struct page *from) > { > - struct page *kto = page_address(to); > - struct page *kfrom = page_address(from); > + void *kto = page_address(to); > + void *kfrom = page_address(from); > > copy_page(kto, kfrom); >
diff --git a/arch/arm64/mm/copypage.c b/arch/arm64/mm/copypage.c index b5447e53cd73..0dea80bf6de4 100644 --- a/arch/arm64/mm/copypage.c +++ b/arch/arm64/mm/copypage.c @@ -16,8 +16,8 @@ void copy_highpage(struct page *to, struct page *from) { - struct page *kto = page_address(to); - struct page *kfrom = page_address(from); + void *kto = page_address(to); + void *kfrom = page_address(from); copy_page(kto, kfrom);
In copy_highpage() the `kto` and `kfrom` local variables are pointers to struct page, but these are used to hold arbitrary pointers to kernel memory . Each call to page_address() returns a void pointer to memory associated with the relevant page, and copy_page() expects void pointers to this memory. This inconsistency was introduced in commit 2563776b41c3 ("arm64: mte: Tags-aware copy_{user_,}highpage() implementations") and while this doesn't appear to be harmful in practice it is clearly wrong. Correct this by making `kto` and `kfrom` void pointers. Fixes: 2563776b41c3 ("arm64: mte: Tags-aware copy_{user_,}highpage() implementations") Signed-off-by: Tong Tiangen <tongtiangen@huawei.com> Acked-by: Mark Rutland <mark.rutland@arm.com> --- arch/arm64/mm/copypage.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)