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[v3,bpf-next,0/3] bpf: Reject attaching fexit to __noreturn functions

Message ID 20250224114606.3500-1-laoar.shao@gmail.com (mailing list archive)
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Series bpf: Reject attaching fexit to __noreturn functions | expand

Message

Yafang Shao Feb. 24, 2025, 11:46 a.m. UTC 
Attaching fexit probes to functions marked with __noreturn may lead to
unpredictable behavior. To avoid this, we will reject attaching probes to
such functions. Currently, there is no ideal solution, so we will hardcode
a check for all __noreturn functions. Since objtool already handles
this, we will leverage its implementation.

Once a more robust solution is found, this workaround can be removed.

v2->v3:
- Remove the need for objtool (Alexei)

v1->v2: https://lore.kernel.org/bpf/20250223062735.3341-1-laoar.shao@gmail.com/
- keep tools/objtool/noreturns.h as is (Josh)
- Add noreturns.h to objtool/sync-check.sh (Josh)
- Add verbose for the reject and simplify the test case (Song)

v1: https://lore.kernel.org/bpf/20250211023359.1570-1-laoar.shao@gmail.com/

Yafang Shao (2):
  bpf: Reject attaching fexit to functions annotated with __noreturn
  selftests/bpf: Add selftest for attaching fexit to __noreturn
    functions

 kernel/bpf/verifier.c                         | 57 +++++++++++++++++++
 .../bpf/prog_tests/fexit_noreturns.c          |  9 +++
 .../selftests/bpf/progs/fexit_noreturns.c     | 15 +++++
 3 files changed, 81 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/fexit_noreturns.c
 create mode 100644 tools/testing/selftests/bpf/progs/fexit_noreturns.c