From: Daniel Borkmann <daniel@iogearbox.net>
To: Jakub Kicinski <kuba@kernel.org>, Prithvi <activprithvi@gmail.com>
Cc: andrii@kernel.org, socketcan@hartkopp.net, mkl@pengutronix.de,
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: Mon, 5 Jan 2026 23:11:28 +0100 [thread overview]
Message-ID: <993342e7-edd3-4c65-aaf9-673255ea11da@iogearbox.net> (raw)
In-Reply-To: <20260102120405.34613b68@kernel.org>
On 1/2/26 9:04 PM, Jakub Kicinski wrote:
[...]
>
> Without looking too deeply - XDP has historically left the new space
> uninitialized after push, expecting programs to immediately write the
> headers in that space.
Correct, and the same also holds true for tc BPF programs. This is an
optimization given zero'ing and then again immediately write of the
headers from the BPF program cannot be optimized by the compiler into
just the latter write. Additionally, load/attachments of these programs
require root capabilities (e.g. cap_bpf, cap_perfmon, cap_net_admin).
next prev parent reply other threads:[~2026-01-05 22:37 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
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 [this message]
2025-11-28 17:48 ` Feedback on question about " Prithvi Tambewagh
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