From: Yonghong Song <yonghong.song@linux.dev>
To: Dave Thaler <dthaler1968@googlemail.com>,
'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 08:18:33 -0700 [thread overview]
Message-ID: <ff27a7ba-e3b3-4cd9-85a8-55c10756df5d@linux.dev> (raw)
In-Reply-To: <18d101db038f$f3c2d400$db487c00$@gmail.com>
On 9/10/24 7:44 AM, Dave Thaler wrote:
> 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?
Right. This is equivalent to INT64_MIN/-1. Indeed, we need check and protect for this case as well.
next prev parent reply other threads:[~2024-09-10 15:18 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
2024-09-10 15:18 ` Yonghong Song [this message]
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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