On Tue, Aug 26, 2025 at 03:19:42PM +0800, Yafang Shao wrote:
> Every VMA must have an associated mm_struct, and it is safe to access
Err this isn't true? Pretty sure special VMAs don't have that set.
> outside of RCU. Thus, we can mark it as trusted. With this change, BPF
> helpers can safely access vma->vm_mm to retrieve the associated task
> from the VMA.
On the basis of above don't think this is valid.
>
> Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
> ---
> kernel/bpf/verifier.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index c4f69a9e9af6..984ffbca5cbe 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -7154,6 +7154,10 @@ BTF_TYPE_SAFE_TRUSTED(struct file) {
> struct inode *f_inode;
> };
>
> +BTF_TYPE_SAFE_TRUSTED(struct vm_area_struct) {
> + struct mm_struct *vm_mm;
> +};
> +
> BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct dentry) {
> struct inode *d_inode;
> };
> @@ -7193,6 +7197,7 @@ static bool type_is_trusted(struct bpf_verifier_env *env,
> BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task));
> BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct linux_binprm));
> BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct file));
> + BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct vm_area_struct));
>
> return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_trusted");
> }
> --
> 2.47.3
>
