libbpf: add compile-time OOB warning to bpf_tail_call_static #5898
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Add a compile-time check to bpf_tail_call_static() to warn when a
constant slot(index) >= map->max_entries. This uses a small
BPF_MAP_ENTRIES() macro together with Clang's diagnose_if attribute.
Clang front-end keeps the map type with a '(*max_entries)[N]' field,
so the expression
sizeof(*(m)->max_entries) / sizeof(**(m)->max_entries)
is resolved to N entirely at compile time. This allows diagnose_if()
to emit a warning when a constant slot index is out of range.
Out-of-bounds tail calls are currently silent no-ops at runtime, so
emitting a compile-time warning helps detect logic errors earlier.
This is currently limited to Clang (due to diagnose_if) and only for
constant indices, but should still catch the common cases.
Signed-off-by: Hoyeon Lee <[email protected]>
Author
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Upstream branch: 9621eb6 |
Author
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=999162 expired. Closing PR. |
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Pull request for series with
subject: libbpf: add compile-time OOB warning to bpf_tail_call_static
version: 2
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=999162