# \[PATCH bpf 0/2\] bpf, fix for subprogs with tailcalls

- From: John Fastabend \<john.fastabend@gmail.com\>
- Date: 2021-06-30 19:41:06 
- List: netdev
- Page: https://ratatoskr.run/netdev/2021/06/7772666
- Thread: https://ratatoskr.run/bpf/2021/06/7772666/t.md

```text
This fixes a use-after-free when using subprogs and tailcalls and adds
a test case to trigger the use-after-free.

John Fastabend (2):
  bpf: track subprog poke correctly, fix use-after-free
  bpf: selftest to verify mixing bpf2bpf calls and tailcalls with insn
    patch

 arch/x86/net/bpf_jit_comp.c                   |  4 ++
 include/linux/bpf.h                           |  1 +
 kernel/bpf/core.c                             |  7 +++-
 kernel/bpf/verifier.c                         | 39 ++++---------------
 .../selftests/bpf/prog_tests/tailcalls.c      | 36 ++++++++++++-----
 .../selftests/bpf/progs/tailcall_bpf2bpf4.c   | 21 +++++++++-
 6 files changed, 64 insertions(+), 44 deletions(-)

-- 
2.25.1

```