bpf: Allow overwriting referenced dynptr when refcnt > 1

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The verifier currently does not allow overwriting a referenced dynptr's
stack slot to prevent resource leak. This is because referenced dynptr
holds additional resources that requires calling specific helpers to
release. This limitation can be relaxed when there are multiple copies
of the same dynptr. Whether it is the orignial dynptr or one of its
clones, as long as there exists at least one other dynptr with the same
ref_obj_id (to be used to release the reference), its stack slot should
be allowed to be overwritten.

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260406150548.1354271-2-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Amery Hung 2026-04-06 08:05:47 -07:00 • committed by Alexei Starovoitov

parent cac16ce1e3

commit 017f5c4ef7

1 changed files with 21 additions and 2 deletions

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kernel/bpf/verifier.c

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