Re: [PATCH v4 3/4] uacce: implement mremap in uacce_vm_ops to return -EPERM

[Zhangfei Gao]

On Wed, 22 Oct 2025 at 10:11, Chenghai Huang <huangchenghai2@xxxxxxxxxx> wrote:
>
> From: Yang Shen <shenyang39@xxxxxxxxxx>
>
> The current uacce_vm_ops does not support the mremap operation of
> vm_operations_struct. Implement .mremap to return -EPERM to remind
> users.
>
> The reason we need to explicitly disable mremap is that when the
> driver does not implement .mremap, it uses the default mremap
> method. This could lead to a risk scenario:
>
> An application might first mmap address p1, then mremap to p2,
> followed by munmap(p1), and finally munmap(p2). Since the default
> mremap copies the original vma's vm_private_data (i.e., q) to the
> new vma, both munmap operations would trigger vma_close, causing
> q->qfr to be freed twice(qfr will be set to null here, so repeated
> release is ok).
>
> Fixes: 015d239ac014 ("uacce: add uacce driver")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Yang Shen <shenyang39@xxxxxxxxxx>
> Signed-off-by: Chenghai Huang <huangchenghai2@xxxxxxxxxx>

Acked-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>

Thanks