From: Jakub Kicinski <kuba@kernel.org>
To: Oliver Hartkopp <socketcan@hartkopp.net>
Cc: mkl@pengutronix.de, Prithvi <activprithvi@gmail.com>,
andrii@kernel.org, linux-can@vger.kernel.org,
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
netdev@vger.kernel.org
Subject: Re: [bpf, xdp] headroom - was: Re: Question about to KMSAN: uninit-value in can_receive
Date: Tue, 6 Jan 2026 16:23:06 -0800 [thread overview]
Message-ID: <20260106162306.0649424c@kernel.org> (raw)
In-Reply-To: <904fa297-b657-4f5b-9999-b8cfcc11bfa9@hartkopp.net>
On Tue, 6 Jan 2026 13:04:41 +0100 Oliver Hartkopp wrote:
> When such skb is echo'ed back after successful transmission via
> netif_rx() this leads to skb->skb_iif = skb->dev->ifindex;
>
> To prevent a loopback the CAN frame must not be sent back to the
> originating interface - even when it has been routed to different CAN
> interfaces in the meantime (which always overwrites skb_iif).
>
> Therefore we need to maintain the "real original" incoming interface.
Alternatively perhaps for this particular use case you could use
something like metadata_dst to mark the frame as forwarded / annotate
with the originating ifindex?
next prev parent reply other threads:[~2026-01-07 0:23 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-05 13:36 [syzbot] [can?] KMSAN: uninit-value in can_receive (3) syzbot
2025-11-17 17:30 ` Question about to KMSAN: uninit-value in can_receive Prithvi Tambewagh
2025-11-29 17:04 ` Oliver Hartkopp
2025-11-30 12:04 ` Feedback provided on question about " Prithvi Tambewagh
2025-11-30 12:44 ` Question about to " Oliver Hartkopp
2025-11-30 17:29 ` Prithvi Tambewagh
2025-11-30 19:09 ` Oliver Hartkopp
2025-12-07 18:45 ` Prithvi
2025-12-20 17:33 ` Prithvi
2025-12-21 18:29 ` [bpf, xdp] headroom - was: " Oliver Hartkopp
2025-12-21 19:06 ` Marc Kleine-Budde
2025-12-21 19:42 ` Oliver Hartkopp
2026-01-02 15:36 ` Prithvi
2026-01-02 20:04 ` Jakub Kicinski
2026-01-03 12:20 ` Oliver Hartkopp
2026-01-04 15:42 ` Jakub Kicinski
2026-01-05 13:47 ` Oliver Hartkopp
2026-01-05 23:26 ` Jakub Kicinski
2026-01-06 12:04 ` Oliver Hartkopp
2026-01-07 0:23 ` Jakub Kicinski [this message]
2026-01-07 15:34 ` Oliver Hartkopp
2026-01-07 19:10 ` Oliver Hartkopp
2026-01-08 15:17 ` Jakub Kicinski
2026-01-08 16:27 ` Oliver Hartkopp
2026-01-05 21:30 ` Andrii Nakryiko
2026-01-05 22:11 ` Daniel Borkmann
2025-11-28 17:48 ` Feedback on question about " Prithvi Tambewagh
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