kernel/linux.git/mm/memfd.c, branch v7.0-rc7

mm: update shmem_[kernel]_file_*() functions to use vma_flags_t

2026-02-12T23:42:58+00:00

In order to be able to use only vma_flags_t in vm_area_desc we must adjust shmem file setup functions to operate in terms of vma_flags_t rather than vm_flags_t. This patch makes this change and updates all callers to use the new functions. No functional changes intended. [akpm@linux-foundation.org: comment fixes, per Baolin] Link: https://lkml.kernel.org/r/736febd280eb484d79cef5cf55b8a6f79ad832d2.1769097829.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Baolin Wang Reviewed-by: Jarkko Sakkinen Reviewed-by: Liam R. Howlett Cc: Barry Song Cc: David Hildenbrand Cc: Dev Jain Cc: Jason Gunthorpe Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Zi Yan Cc: "Darrick J. Wong" Cc: Damien Le Moal Cc: Yury Norov Cc: Chris Mason Cc: Pedro Falcato Signed-off-by: Andrew Morton

mm: update hugetlbfs to use VMA flags on mmap_prepare

2026-02-12T23:42:57+00:00

In order to update all mmap_prepare users to utilising the new VMA flags type vma_flags_t and associated helper functions, we start by updating hugetlbfs which has a lot of additional logic that requires updating to make this change. This is laying the groundwork for eliminating the vm_flags_t from struct vm_area_desc and using vma_flags_t only, which further lays the ground for removing the deprecated vm_flags_t type altogether. No functional changes intended. Link: https://lkml.kernel.org/r/9226bec80c9aa3447cc2b83354f733841dba8a50.1769097829.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Liam R. Howlett Cc: Baolin Wang Cc: Barry Song Cc: David Hildenbrand Cc: Dev Jain Cc: Jason Gunthorpe Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Zi Yan Cc: Damien Le Moal Cc: "Darrick J. Wong" Cc: Jarkko Sakkinen Cc: Yury Norov Cc: Chris Mason Cc: Pedro Falcato Signed-off-by: Andrew Morton

mm: add SPDX id lines to some mm source files

2026-02-06T23:47:16+00:00

Some of the memory management source files are missing SPDX-License-Identifier lines. Add appropriate IDs to these files (mostly GPL-2.0, but one LGPL-2.1). Link: https://lkml.kernel.org/r/20260204213101.1754183-1-tim.bird@sony.com Signed-off-by: Tim Bird Signed-off-by: Andrew Morton

memfd: export alloc_file()

2026-01-27T03:03:47+00:00

Patch series "mm: memfd_luo hotfixes". This series contains a couple of fixes for memfd preservation using LUO. This patch (of 3): The Live Update Orchestrator's (LUO) memfd preservation works by preserving all the folios of a memfd, re-creating an empty memfd on the next boot, and then inserting back the preserved folios. Currently it creates the file by directly calling shmem_file_setup(). This leaves out other work done by alloc_file() like setting up the file mode, flags, or calling the security hooks. Export alloc_file() to let memfd_luo use it. Rename it to memfd_alloc_file() since it is no longer private and thus needs a subsystem prefix. Link: https://lkml.kernel.org/r/20260122151842.4069702-1-pratyush@kernel.org Link: https://lkml.kernel.org/r/20260122151842.4069702-2-pratyush@kernel.org Signed-off-by: Pratyush Yadav (Google) Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Pasha Tatashin Cc: Baolin Wang Cc: Hugh Dickins Signed-off-by: Andrew Morton

Merge tag 'selinux-pr-20251201' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

2025-12-03T18:45:47+00:00

Pull selinux updates from Paul Moore: - Improve the granularity of SELinux labeling for memfd files Currently when creating a memfd file, SELinux treats it the same as any other tmpfs, or hugetlbfs, file. While simple, the drawback is that it is not possible to differentiate between memfd and tmpfs files. This adds a call to the security_inode_init_security_anon() LSM hook and wires up SELinux to provide a set of memfd specific access controls, including the ability to control the execution of memfds. As usual, the commit message has more information. - Improve the SELinux AVC lookup performance Adopt MurmurHash3 for the SELinux AVC hash function instead of the custom hash function currently used. MurmurHash3 is already used for the SELinux access vector table so the impact to the code is minimal, and performance tests have shown improvements in both hash distribution and latency. See the commit message for the performance measurments. - Introduce a Kconfig option for the SELinux AVC bucket/slot size While we have the ability to grow the number of AVC hash buckets today, the size of the buckets (slot size) is fixed at 512. This pull request makes that slot size configurable at build time through a new Kconfig knob, CONFIG_SECURITY_SELINUX_AVC_HASH_BITS. * tag 'selinux-pr-20251201' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: selinux: improve bucket distribution uniformity of avc_hash() selinux: Move avtab_hash() to a shared location for future reuse selinux: Introduce a new config to make avc cache slot size adjustable memfd,selinux: call security_inode_init_security_anon()

Merge tag 'vfs-6.19-rc1.fd_prepare.fs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-12-02T01:32:07+00:00

Pull fd prepare updates from Christian Brauner: "This adds the FD_ADD() and FD_PREPARE() primitive. They simplify the common pattern of get_unused_fd_flags() + create file + fd_install() that is used extensively throughout the kernel and currently requires cumbersome cleanup paths. FD_ADD() - For simple cases where a file is installed immediately: fd = FD_ADD(O_CLOEXEC, vfio_device_open_file(device)); if (fd < 0) vfio_device_put_registration(device); return fd; FD_PREPARE() - For cases requiring access to the fd or file, or additional work before publishing: FD_PREPARE(fdf, O_CLOEXEC, sync_file->file); if (fdf.err) { fput(sync_file->file); return fdf.err; } data.fence = fd_prepare_fd(fdf); if (copy_to_user((void __user *)arg, &data, sizeof(data))) return -EFAULT; return fd_publish(fdf); The primitives are centered around struct fd_prepare. FD_PREPARE() encapsulates all allocation and cleanup logic and must be followed by a call to fd_publish() which associates the fd with the file and installs it into the caller's fdtable. If fd_publish() isn't called, both are deallocated automatically. FD_ADD() is a shorthand that does fd_publish() immediately and never exposes the struct to the caller. I've implemented this in a way that it's compatible with the cleanup infrastructure while also being usable separately. IOW, it's centered around struct fd_prepare which is aliased to class_fd_prepare_t and so we can make use of all the basica guard infrastructure" * tag 'vfs-6.19-rc1.fd_prepare.fs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (42 commits) io_uring: convert io_create_mock_file() to FD_PREPARE() file: convert replace_fd() to FD_PREPARE() vfio: convert vfio_group_ioctl_get_device_fd() to FD_ADD() tty: convert ptm_open_peer() to FD_ADD() ntsync: convert ntsync_obj_get_fd() to FD_PREPARE() media: convert media_request_alloc() to FD_PREPARE() hv: convert mshv_ioctl_create_partition() to FD_ADD() gpio: convert linehandle_create() to FD_PREPARE() pseries: port papr_rtas_setup_file_interface() to FD_ADD() pseries: convert papr_platform_dump_create_handle() to FD_ADD() spufs: convert spufs_gang_open() to FD_PREPARE() papr-hvpipe: convert papr_hvpipe_dev_create_handle() to FD_PREPARE() spufs: convert spufs_context_open() to FD_PREPARE() net/socket: convert __sys_accept4_file() to FD_ADD() net/socket: convert sock_map_fd() to FD_ADD() net/kcm: convert kcm_ioctl() to FD_PREPARE() net/handshake: convert handshake_nl_accept_doit() to FD_PREPARE() secretmem: convert memfd_secret() to FD_ADD() memfd: convert memfd_create() to FD_ADD() bpf: convert bpf_token_create() to FD_PREPARE() ...

memfd: convert memfd_create() to FD_ADD()

2025-11-28T11:42:34+00:00

Link: https://patch.msgid.link/20251123-work-fd-prepare-v4-25-b6efa1706cfd@kernel.org Signed-off-by: Christian Brauner

mm/memfd: fix information leak in hugetlb folios

2025-11-24T22:25:17+00:00

When allocating hugetlb folios for memfd, three initialization steps are missing: 1. Folios are not zeroed, leading to kernel memory disclosure to userspace 2. Folios are not marked uptodate before adding to page cache 3. hugetlb_fault_mutex is not taken before hugetlb_add_to_page_cache() The memfd allocation path bypasses the normal page fault handler (hugetlb_no_page) which would handle all of these initialization steps. This is problematic especially for udmabuf use cases where folios are pinned and directly accessed by userspace via DMA. Fix by matching the initialization pattern used in hugetlb_no_page(): - Zero the folio using folio_zero_user() which is optimized for huge pages - Mark it uptodate with folio_mark_uptodate() - Take hugetlb_fault_mutex before adding to page cache to prevent races The folio_zero_user() change also fixes a potential security issue where uninitialized kernel memory could be disclosed to userspace through read() or mmap() operations on the memfd. Link: https://lkml.kernel.org/r/20251112145034.2320452-1-kartikey406@gmail.com Fixes: 89c1905d9c14 ("mm/gup: introduce memfd_pin_folios() for pinning memfd folios") Signed-off-by: Deepanshu Kartikey Reported-by: syzbot+f64019ba229e3a5c411b@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/20251112031631.2315651-1-kartikey406@gmail.com/ [v1] Closes: https://syzkaller.appspot.com/bug?extid=f64019ba229e3a5c411b Suggested-by: Oscar Salvador Suggested-by: David Hildenbrand Tested-by: syzbot+f64019ba229e3a5c411b@syzkaller.appspotmail.com Acked-by: Oscar Salvador Acked-by: David Hildenbrand (Red Hat) Acked-by: Hugh Dickins Cc: Vivek Kasireddy Cc: Jason Gunthorpe Cc: Jason Gunthorpe (v2) Cc: Christoph Hellwig (v6) Cc: Dave Airlie Cc: Gerd Hoffmann Cc: Signed-off-by: Andrew Morton

memfd,selinux: call security_inode_init_security_anon()

2025-10-22T23:28:27+00:00

Prior to this change, no security hooks were called at the creation of a memfd file. It means that, for SELinux as an example, it will receive the default type of the filesystem that backs the in-memory inode. In most cases, that would be tmpfs, but if MFD_HUGETLB is passed, it will be hugetlbfs. Both can be considered implementation details of memfd. It also means that it is not possible to differentiate between a file coming from memfd_create and a file coming from a standard tmpfs mount point. Additionally, no permission is validated at creation, which differs from the similar memfd_secret syscall. Call security_inode_init_security_anon during creation. This ensures that the file is setup similarly to other anonymous inodes. On SELinux, it means that the file will receive the security context of its task. The ability to limit fexecve on memfd has been of interest to avoid potential pitfalls where /proc/self/exe or similar would be executed [1][2]. Reuse the "execute_no_trans" and "entrypoint" access vectors, similarly to the file class. These access vectors may not make sense for the existing "anon_inode" class. Therefore, define and assign a new class "memfd_file" to support such access vectors. Guard these changes behind a new policy capability named "memfd_class". [1] https://crbug.com/1305267 [2] https://lore.kernel.org/lkml/20221215001205.51969-1-jeffxu@google.com/ Signed-off-by: Thiébaud Weksteen Reviewed-by: Stephen Smalley Tested-by: Stephen Smalley Acked-by: Hugh Dickins [PM: subj tweak] Signed-off-by: Paul Moore

mm/memfd: remove redundant casts

2025-09-21T21:22:00+00:00

MFD_ALL_FLAGS is already an unsigned int. Remove redundant casts to unsigned int. Link: https://lkml.kernel.org/r/efbbe6093b64a5b19f974871d5262d6e75dff2c0.1756639225.git.joeypabalinas@gmail.com Signed-off-by: Joey Pabalinas Cc: Baolin Wang Cc: Hugh Dickins Cc: Joey Pabalinas Signed-off-by: Andrew Morton