Re: [PATCH 5.4.y 2/3] mm: update memfd seal write check to include F_SEAL_WRITE

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: 28464bbb2ddc199433383994bcb9600c8034afa1

WARNING: Author mismatch between patch and upstream commit:
Backport author: Isaac J. Manjarres <isaacmanjarres@google.com>
Commit author: Lorenzo Stoakes <lstoakes@gmail.com>

Status in newer kernel trees:
6.15.y | Present (exact SHA1)
6.12.y | Present (exact SHA1)
6.6.y | Not found
6.1.y | Not found
5.15.y | Not found
5.10.y | Not found

Note: The patch differs from the upstream commit:
---
1:  28464bbb2ddc ! 1:  3f153c98f29a mm: update memfd seal write check to include F_SEAL_WRITE
    @@ Metadata
      ## Commit message ##
         mm: update memfd seal write check to include F_SEAL_WRITE
     
    +    [ Upstream commit 28464bbb2ddc199433383994bcb9600c8034afa1 ]
    +
         The seal_check_future_write() function is called by shmem_mmap() or
         hugetlbfs_file_mmap() to disallow any future writable mappings of an memfd
         sealed this way.
    @@ Commit message
         Cc: Mike Kravetz <mike.kravetz@oracle.com>
         Cc: Muchun Song <muchun.song@linux.dev>
         Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    +    Cc: stable@vger.kernel.org
    +    Signed-off-by: Isaac J. Manjarres <isaacmanjarres@google.com>
     
      ## fs/hugetlbfs/inode.c ##
     @@ fs/hugetlbfs/inode.c: static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
    - 	vm_flags_set(vma, VM_HUGETLB | VM_DONTEXPAND);
    + 	vma->vm_flags |= VM_HUGETLB | VM_DONTEXPAND;
      	vma->vm_ops = &hugetlb_vm_ops;
      
     -	ret = seal_check_future_write(info->seals, vma);
    @@ fs/hugetlbfs/inode.c: static int hugetlbfs_file_mmap(struct file *file, struct v
      
     
      ## include/linux/mm.h ##
    -@@ include/linux/mm.h: static inline void mem_dump_obj(void *object) {}
    - #endif
    +@@ include/linux/mm.h: static inline int pages_identical(struct page *page1, struct page *page2)
    + }
      
      /**
     - * seal_check_future_write - Check for F_SEAL_FUTURE_WRITE flag and handle it
    @@ include/linux/mm.h: static inline void mem_dump_obj(void *object) {}
     
      ## mm/shmem.c ##
     @@ mm/shmem.c: static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
    - 	struct shmem_inode_info *info = SHMEM_I(inode);
    + 	struct shmem_inode_info *info = SHMEM_I(file_inode(file));
      	int ret;
      
     -	ret = seal_check_future_write(info->seals, vma);

---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| 5.4                       | Success     | Success    |