bpf: Drop special callback reference handling

2024-11-11T16:18:55Z

Logic to prevent callbacks from acquiring new references for the program (i.e. leaving acquired references), and releasing caller references (i.e. those acquired in parent frames) was introduced in commit 9d9d00ac29d0 ("bpf: Fix reference state management for synchronous callbacks"). This was necessary because back then, the verifier simulated each callback once (that could potentially be executed N times, where N can be zero). This meant that callbacks that left lingering resources or cleared caller resources could do it more than once, operating on undefined state or leaking memory. With the fixes to callback verification in commit ab5cfac139ab ("bpf: verify callbacks as if they are called unknown number of times"), all of this extra logic is no longer necessary. Hence, drop it as part of this commit. Cc: Eduard Zingerman Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20241109231430.2475236-3-memxor@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko

selftests/bpf: Add tests for reference state fixes for callbacks

2022-08-25T00:54:40Z

These are regression tests to ensure we don't end up in invalid runtime state for helpers that execute callbacks multiple times. It exercises the fixes to verifier callback handling for reference state in previous patches. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20220823013226.24988-1-memxor@gmail.com Signed-off-by: Alexei Starovoitov

kernel.git/tools/testing/selftests/bpf/prog_tests/cb_refs.c, branch master

bpf: Drop special callback reference handling

selftests/bpf: Add tests for reference state fixes for callbacks