On 11/25/23 23:56, Oleg Nesterov wrote:
On 11/25, Rong Tao wrote:
+static int prctl_get_vma(unsigned long opt, unsigned long addr,
+ unsigned long buf, unsigned long arg)
+{
+ struct mm_struct *mm = current->mm;
+ const char __user *u_buf;
+ int error;
+
+ switch (opt) {
+ case PR_GET_VMA_ANON_NAME:
+ const struct anon_vma_name *anon_name = NULL;
+
+ u_buf = (const char __user *)buf;
+ error = 0;
+
+ mmap_read_lock(mm);
+ anon_name = madvise_get_anon_name(mm, addr);
+ if (!anon_name) {
+ mmap_read_unlock(mm);
+ error = -EFAULT;
may be another error code makes sense to distinguish this case from
the copy_to_user() failure?
+ break;
+ }
+
+ if (copy_to_user((char __user *)u_buf, anon_name->name,
+ strlen(anon_name->name) + 1))
+ error = -EFAULT;
and I guess you can simplify this code a bit,
anon_name = madvise_get_anon_name(...);
if (!anon_name || copy_to_user(...))
error = -EFAULT;
Thanks a lot, I just modify the code, please review.
mmap_read_unlock(mm);
anon_vma_name_put(anon_name); // safe if anon_name == NULL;
+const struct anon_vma_name *madvise_get_anon_name(struct mm_struct *mm,
+ unsigned long start)
+{
+ struct vm_area_struct *vma;
+ struct anon_vma_name *anon_name;
+
+ vma = find_vma(mm, start);
+ if (vma) {
+ anon_name = anon_vma_name(vma);
+ if (anon_name) {
+ anon_vma_name_get(anon_name);
+ return anon_name;
+ }
+ }
+
+ return NULL;
Again, afaics this can be simplified,
struct anon_vma_name *anon_name = NULL;
vma = find_vma(mm, start);
if (vma) {
anon_name = anon_vma_name(vma);
anon_vma_name_get(anon_name);
}
return anon_name;
Oleg.
Thanks again.
Rong Tao
