From: Simon Horman <horms@kernel.org>
To: Breno Leitao <leitao@debian.org>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
asantostc@gmail.com, gustavold@gmail.com, kernel-team@meta.com
Subject: Re: [PATCH net] netconsole: don't drop the last byte of a full-sized message
Date: Thu, 18 Jun 2026 10:13:01 +0100 [thread overview]
Message-ID: <20260618091301.GH827683@horms.kernel.org> (raw)
In-Reply-To: <20260616-max_print_chunk-v1-1-8dc125d67083@debian.org>
On Tue, Jun 16, 2026 at 09:09:52AM -0700, Breno Leitao wrote:
> nt->buf is exactly MAX_PRINT_CHUNK bytes, but scnprintf() reserves one
> byte for its NUL terminator, so a non-fragmented payload of exactly
> MAX_PRINT_CHUNK loses its last byte (emitted as a stray NUL in the
> release path). Grow nt->buf to MAX_PRINT_CHUNK + 1 and bound the
> scnprintf() calls with sizeof(nt->buf); the transmitted length stays
> capped at MAX_PRINT_CHUNK.
>
> Alternatively, nt->buf could be left at MAX_PRINT_CHUNK and the NUL byte
> reserved by routing exactly-MAX_PRINT_CHUNK payloads to fragmentation
> ('len < MAX_PRINT_CHUNK'), at the cost of fragmenting those messages.
> But it would look less sane, thus the current approach.
>
> Fixes: c62c0a17f9b7 ("netconsole: Append kernel version to message")
> Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
prev parent reply other threads:[~2026-06-18 9:13 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-16 16:09 [PATCH net] netconsole: don't drop the last byte of a full-sized message Breno Leitao
2026-06-18 9:13 ` Simon Horman [this message]
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