diff mbox series

[bpf-next,1/2] bpf: Add __rcu_read_{lock,unlock} into btf id deny list

Message ID 20230424161104.3737-2-laoar.shao@gmail.com (mailing list archive)
State Accepted
Commit a0c109dcafb15b8bee187c49fb746779374f60f0
Delegated to: BPF
Headers show
Series bpf: Fix issues caused by bpf trampoline | expand

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bpf/vmtest-bpf-next-PR success PR summary
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bpf/vmtest-bpf-next-VM_Test-20 fail Logs for test_progs_no_alu32 on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-21 fail Logs for test_progs_no_alu32 on x86_64 with gcc
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bpf/vmtest-bpf-next-VM_Test-33 success Logs for test_verifier on s390x with gcc
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 20 this patch: 20
netdev/cc_maintainers warning 2 maintainers not CCed: martin.lau@linux.dev song@kernel.org
netdev/build_clang fail Errors and warnings before: 13 this patch: 13
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
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Commit Message

Yafang Shao April 24, 2023, 4:11 p.m. UTC 
The tracing recursion prevention mechanism must be protected by rcu, that
leaves __rcu_read_{lock,unlock} unprotected by this mechanism. If we trace
them, the recursion will happen. Let's add them into the btf id deny list.

When CONFIG_PREEMPT_RCU is enabled, it can be reproduced with a simple bpf
program as such:
  SEC("fentry/__rcu_read_lock")
  int fentry_run()
  {
      return 0;
  }

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 kernel/bpf/verifier.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox series

Patch

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 5dae11e..83fb94f 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -18645,6 +18645,10 @@  int bpf_check_attach_target(struct bpf_verifier_log *log,
 BTF_ID(func, preempt_count_add)
 BTF_ID(func, preempt_count_sub)
 #endif
+#ifdef CONFIG_PREEMPT_RCU
+BTF_ID(func, __rcu_read_lock)
+BTF_ID(func, __rcu_read_unlock)
+#endif
 BTF_SET_END(btf_id_deny)
 
 static bool can_be_sleepable(struct bpf_prog *prog)