bpf: improve deduction of 64-bit bounds from 32-bit bounds

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Add a few interesting cases in which we can tighten 64-bit bounds based
on newly learnt information about 32-bit bounds. E.g., when full u64/s64
registers are used in BPF program, and then eventually compared as
u32/s32. The latter comparison doesn't change the value of full
register, but it does impose new restrictions on possible lower 32 bits
of such full registers. And we can use that to derive additional full
register bounds information.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20231102033759.2541186-8-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Andrii Nakryiko 2023-11-01 20:37:49 -07:00 • committed by Alexei Starovoitov

parent 6593f2e674

commit c51d5ad654

1 changed files with 44 additions and 0 deletions

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kernel/bpf/verifier.c

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