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From: Dave Thaler <dthaler1968@googlemail.com>
To: "'Yonghong Song'" <yonghong.song@linux.dev>,
	"'Alexei Starovoitov'" <alexei.starovoitov@gmail.com>,
	"'Zac Ecob'" <zacecob@protonmail.com>,
	"'Daniel Borkmann'" <daniel@iogearbox.net>
Cc: <bpf@vger.kernel.org>
Subject: RE: Kernel oops caused by signed divide
Date: Tue, 10 Sep 2024 07:44:33 -0700	[thread overview]
Message-ID: <18d101db038f$f3c2d400$db487c00$@gmail.com> (raw)
In-Reply-To: <1058c69c-3e2c-4c0b-b777-2b0460f443f9@linux.dev>

Yonghong Song wrote: 
[...]
> In verifier, we have
>    /* [R,W]x div 0 -> 0 */
>    /* [R,W]x mod 0 -> [R,W]x */
> 
> What the value for
>    Rx_a sdiv Rx_b -> ?
> where Rx_a = INT64_MIN and Rx_b = -1?
> 
> Should we just do
>    INT64_MIN sdiv -1 -> -1
> or some other values?

What happens for BPF_NEG INT64_MIN?

Dave


  reply	other threads:[~2024-09-10 14:44 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-09-09 17:21 Kernel oops caused by signed divide Zac Ecob
2024-09-09 17:27 ` Yonghong Song
2024-09-09 17:29 ` Alexei Starovoitov
2024-09-09 23:47   ` Yonghong Song
2024-09-10 14:21   ` Yonghong Song
2024-09-10 14:44     ` Dave Thaler [this message]
2024-09-10 15:18       ` Yonghong Song
2024-09-10 15:21         ` Alexei Starovoitov
2024-09-10 18:12           ` Yonghong Song
2024-09-10 15:21     ` Alexei Starovoitov
2024-09-10 18:02       ` Yonghong Song
2024-09-10 18:25         ` Alexei Starovoitov
2024-09-10 19:32           ` Yonghong Song
2024-09-10 21:53             ` Alexei Starovoitov
2024-09-10 22:00               ` Yonghong Song
2024-09-10 22:43               ` Andrii Nakryiko

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