From: Jakub Kicinski <kuba@kernel.org>
To: RUITONG LIU <cnitlrt@gmail.com>
Cc: netdev@vger.kernel.org, jhs@mojatatu.com,
xiyou.wangcong@gmail.com, jiri@resnulli.us, davem@davemloft.net,
edumazet@google.com, pabeni@redhat.com, horms@kernel.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Shuyuan Liu <L0x1c3r@gmail.com>
Subject: Re: [PATCH v2] net/sched: act_skbedit: fix divide-by-zero in tcf_skbedit_hash()
Date: Fri, 13 Feb 2026 08:24:30 -0800 [thread overview]
Message-ID: <20260213082430.7c4ce0af@kernel.org> (raw)
In-Reply-To: <CAK55_s5pR7KTMzNkHySK+XoGtv-WFdVe77PzD3+7uPuytYDNYg@mail.gmail.com>
On Thu, 12 Feb 2026 20:29:20 -0700 RUITONG LIU wrote:
> With queue_mapping = 0 and queue_mapping_max = 65535, the existing
> validation passes because it only checks queue_mapping_max <
> queue_mapping, which is false. The code then computes the inclusive
> range size:
> mapping_mod = queue_mapping_max - queue_mapping + 1 = 65536.
> However, mapping_mod is stored in a u16, so 65536 wraps to 0. This 0
> value is later used as the divisor in a modulo operation (hash %
> mapping_mod), causing a divide-by-zero.
I see, thanks, could you please use the version of the patch
that Eric posted? It's much more intuitive than checking for 0.
Maybe use U16_MAX instead of 0xffff, too
next prev parent reply other threads:[~2026-02-13 16:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-11 18:48 [PATCH] net/sched: act_skbedit: fix divide-by-zero in tcf_skbedit_hash() Ruitong Liu
2026-02-11 19:07 ` Eric Dumazet
2026-02-11 19:43 ` [PATCH v2] " Ruitong Liu
2026-02-13 2:08 ` Jakub Kicinski
2026-02-13 3:29 ` RUITONG LIU
2026-02-13 16:24 ` Jakub Kicinski [this message]
2026-02-13 17:59 ` [PATCH v3] " Ruitong Liu
2026-02-18 1:29 ` Jakub Kicinski
2026-02-18 1:40 ` patchwork-bot+netdevbpf
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