static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
{
struct shmem_inode_info *info = SHMEM_I(file_inode(file));
+ int ret;
- if (info->seals & F_SEAL_FUTURE_WRITE) {
- /*
- * New PROT_WRITE and MAP_SHARED mmaps are not allowed when
- * "future write" seal active.
- */
- if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE))
- return -EPERM;
-
- /*
- * Since an F_SEAL_FUTURE_WRITE sealed memfd can be mapped as
- * MAP_SHARED and read-only, take care to not allow mprotect to
- * revert protections on such mappings. Do this only for shared
- * mappings. For private mappings, don't need to mask
- * VM_MAYWRITE as we still want them to be COW-writable.
- */
- if (vma->vm_flags & VM_SHARED)
- vma->vm_flags &= ~(VM_MAYWRITE);
- }
+ ret = seal_check_future_write(info->seals, vma);
+ if (ret)
+ return ret;
/* arm64 - allow memory tagging on RAM-based files */
vma->vm_flags |= VM_MTE_ALLOWED;
pgoff_t offset, max_off;
ret = -ENOMEM;
- if (!shmem_inode_acct_block(inode, 1))
+ if (!shmem_inode_acct_block(inode, 1)) {
+ /*
+ * We may have got a page, returned -ENOENT triggering a retry,
+ * and now we find ourselves with -ENOMEM. Release the page, to
+ * avoid a BUG_ON in our caller.
+ */
+ if (unlikely(*pagep)) {
+ put_page(*pagep);
+ *pagep = NULL;
+ }
goto out;
+ }
if (!*pagep) {
page = shmem_alloc_page(gfp, info, pgoff);