bpf: Give vmlinux BTF init its own mutex

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bpf_get_btf_vmlinux() serializes the lazy vmlinux BTF parse with
bpf_verifier_lock, the same mutex bpf_check() holds across the whole
verification of an unprivileged program (if enabled; it's disabled
by default). The latter can potentially stall the mutex holder for
a long time (e.g. via userfaultfd), and therefore block first-time
bpf_get_btf_vmlinux() caller from any context, including privileged
program loads.

Give the vmlinux BTF initialization a dedicated btf_vmlinux_lock so
it is independent of the unprivileged verification mutex. The parse
only needs mutual exclusion against itself.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20260708211537.371874-3-daniel@iogearbox.net
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

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Daniel Borkmann 2026-07-08 23:15:35 +02:00 • committed by Kumar Kartikeya Dwivedi

parent 92863e6780

commit 5e5e94d87d

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2 changed files with 5 additions and 4 deletions

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2

kernel/bpf/btf.c

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7

kernel/bpf/verifier.c

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