[PATCH bpf-next v1 0/5] Fix kptr dtor deadlock

[Kumar Kartikeya Dwivedi <memxor@gmail.com>]

Referenced kptr destruction can run from tracing/NMI contexts through
bpf_obj_drop() and map value update/delete paths, reaching NMI-unsafe
special field teardown and deadlocks. Justin reported the issue and
iterated on fixes in [0]-[2], and also confirmed the bpf_obj_drop()
reproducer in [3].

This series rejects unsafe obj drops from non-iterator tracing programs,
limits map value recycle to NMI-safe field cancellation, and adds
focused selftests for the obj_drop(), NMI delete, and recycle teardown
cases.

See patches for details.

  [0]: https://lore.kernel.org/bpf/20260505150851.3090688-1-utilityemal77@gmail.com
  [1]: https://lore.kernel.org/bpf/20260507175453.1140400-1-utilityemal77@gmail.com
  [2]: https://lore.kernel.org/bpf/20260519011450.1144935-1-utilityemal77@gmail.com
  [3]: https://lore.kernel.org/bpf/agyG3eQwgmoJwmj2@suesslenovo

Justin Suess (2):
  bpf: Reject bpf_obj_drop() from tracing progs
  bpf: Cancel special fields on map value recycle

Kumar Kartikeya Dwivedi (3):
  bpf: Treat non-iterator tracing progs as tracing
  selftests/bpf: Exercise unsafe obj drops from tracing progs
  selftests/bpf: Exercise kptr map update lifetime

 include/linux/bpf.h                           | 30 +++++++
 kernel/bpf/arraymap.c                         |  8 +-
 kernel/bpf/hashtab.c                          | 32 ++++---
 kernel/bpf/syscall.c                          | 27 ++++++
 kernel/bpf/verifier.c                         | 51 +++++++----
 .../selftests/bpf/prog_tests/htab_update.c    |  4 +-
 .../selftests/bpf/prog_tests/map_kptr.c       | 66 ++++++++++++--
 .../selftests/bpf/prog_tests/task_kfunc.c     | 42 ++++++++-
 .../testing/selftests/bpf/progs/htab_update.c |  4 +-
 tools/testing/selftests/bpf/progs/map_kptr.c  | 89 ++++++++++++++++++-
 .../selftests/bpf/progs/task_kfunc_failure.c  | 43 +++++++++
 .../selftests/bpf/progs/task_kfunc_success.c  | 13 ++-
 12 files changed, 352 insertions(+), 57 deletions(-)


base-commit: 50dff00615522f3ec03449680ca23beb4cfc549c
-- 
2.53.0