[GIT PULL for v7.2] vfs fixes

[Christian Brauner]

Hey Linus,

/* Summary */

This contains last fixes for the current development cycle:

- Don't warn when a mount is completed from another user namespace.

  fsopen() records the caller's user namespace in fc->user_ns and hands
  back an ordinary file descriptor. The task that calls
  fsconfig(FSCONFIG_CMD_CREATE) doesn't have to be the one that created
  the context, and mount_capable() lets it through as long as the caller
  has CAP_SYS_ADMIN over fc->user_ns, which anyone in an ancestor
  namespace does. So fc->user_ns != current_user_ns() is something an
  unprivileged user can arrange.

  Both overlayfs and binfmt_misc WARN_ON() that. Overlayfs already
  has the same check as a plain error return in ovl_parse_param(). Drop
  the WARN_ON() and just refuse. Add selftests for both cases.

- Reject pid allocations through dead ancestor pid namespaces.

  Require PIDNS_ADDING in every namespace that will receive the pid
  before publishing any of them. That preserves the invariant that
  free_pid() never decrements pid_allocated in a namespace whose
  child_reaper is no longer live. The existing ENOMEM behavior is
  unchanged.

/* Conflicts */

Merge conflicts with mainline
=============================

No known conflicts.

Merge conflicts with other trees
================================

No known conflicts.

The following changes since commit db2ddb87143519e20a95aa36c60b36107b736a58:

  Linux 7.2-rc7 (2026-08-09 14:54:50 -0700)

are available in the Git repository at:

  git@xxxxxxxxxxxxxxxxxxx:pub/scm/linux/kernel/git/vfs/vfs tags/vfs-7.2-rc8.fixes

for you to fetch changes up to b64a9f67e082e04835ddd69d422a25168d69375b:

  pid: reject allocations through dead ancestor pid namespaces (2026-08-12 12:56:30 +0200)

----------------------------------------------------------------
vfs-7.2-rc8.fixes

Please consider pulling these changes from the signed vfs-7.2-rc8.fixes tag.

Thanks!
Christian

----------------------------------------------------------------
Christian Brauner (4):
      ovl: don't warn when the mount is completed from another user namespace
      binfmt_misc: don't warn when the mount is completed from another user namespace
      selftests/filesystems: test completing a context from another user namespace
      Merge patch series "fs: don't warn when a mount is completed from another user namespace"

Jérémy Jean (1):
      pid: reject allocations through dead ancestor pid namespaces

 fs/binfmt_misc.c                                   |   3 +-
 fs/overlayfs/super.c                               |   3 +-
 kernel/pid.c                                       |   6 +-
 tools/testing/selftests/Makefile                   |   1 +
 .../selftests/filesystems/fscontext_ns/Makefile    |  10 +
 .../filesystems/fscontext_ns/fscontext_ns_test.c   | 239 +++++++++++++++++++++
 6 files changed, 258 insertions(+), 4 deletions(-)
 create mode 100644 tools/testing/selftests/filesystems/fscontext_ns/Makefile
 create mode 100644 tools/testing/selftests/filesystems/fscontext_ns/fscontext_ns_test.c