bpf: Account for preempt and IRQ state in RCU protection

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Disabling preemption or local IRQs keeps the current CPU in an RCU
read-side critical section, but in_rcu_cs() does not account for either
state. The verifier therefore rejects safe kptr accesses and invalidates
pointers when another RCU source ends.

Include preemption-disabled and IRQ-disabled state in in_rcu_cs().
Invalidate RCU-protected pointers on RCU unlock, preempt enable, or IRQ
restore only after the final protection ends.

Signed-off-by: Ning Ding <dingning04@gmail.com>
Link: https://lore.kernel.org/bpf/20260805233940.3966981-2-dingning04@gmail.com
[ kkd: Simplify was_in_rcu_cs on spin unlock and adjust the selftest. ]
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

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Ning Ding 2026-08-05 16:39:33 -07:00 • committed by Kumar Kartikeya Dwivedi

parent 7d008cde75

commit d65739bf93

2 changed files with 16 additions and 6 deletions

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14

kernel/bpf/verifier.c

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8

tools/testing/selftests/bpf/progs/cpumask_failure.c

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