bpf: derive smin/smax from umin/max bounds

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Add smin/smax derivation from appropriate umin/umax values. Previously the
logic was surprisingly asymmetric, trying to derive umin/umax from smin/smax
(if possible), but not trying to do the same in the other direction. A simple
addition to __reg64_deduce_bounds() fixes this.

Added also generic comment about u64/s64 ranges and their relationship.
Hopefully that helps readers to understand all the bounds deductions
a bit better.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Andrii Nakryiko 2023-11-01 20:37:45 -07:00 • committed by Alexei Starovoitov

parent f4c7e88732

commit 93f7378734

1 changed files with 71 additions and 0 deletions

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kernel/bpf/verifier.c

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