From: "Asbjørn Sloth Tønnesen" <ast@fiberby.net>
To: Simon Horman <horms@kernel.org>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Ariel Elior <aelior@marvell.com>,
Manish Chopra <manishc@marvell.com>,
Jiri Pirko <jiri@resnulli.us>,
Pablo Neira Ayuso <pablo@netfilter.org>
Subject: Re: [PATCH net 0/4] net: qede: avoid overruling error codes
Date: Sat, 27 Apr 2024 12:58:38 +0000 [thread overview]
Message-ID: <ab165657-2c69-4b30-a371-6ad7fd28c539@fiberby.net> (raw)
In-Reply-To: <20240427114813.GG516117@kernel.org>
Hi Simon,
Thank you for your review effort.
On 4/27/24 11:48 AM, Simon Horman wrote:
> On Fri, Apr 26, 2024 at 09:12:22AM +0000, Asbjørn Sloth Tønnesen wrote:
>> This series fixes the qede driver, so that
>> qede_parse_flow_attr() and it's subfunctions
>> doesn't get their error codes overruled
>> (ie. turning -EOPNOTSUPP into -EINVAL).
>>
>> ---
>> I have two more patches along the same lines,
>> but they are not yet causing any issues,
>> so I have them destined for net-next.
>> (those are for qede_flow_spec_validate_unused()
>> and qede_flow_parse_ports().)
>>
>> After that I have a series for converting to
>> extack + the final one for validating control
>> flags.
>
> Hi,
>
> I'm fine with these patches so far as the code changes go.
> But it is not clear to me that they are fixing a bug.
>
> If so, I think some explanation should go in the commit messages.
> If not, I think these should be targeted at net-next
> (and not have Fixes tags.
Since I don't have the hardware I didn't try to construct commands, showing
the wrong error code being returned. I could make up some hypothetical commands,
and simulate how they would error. I assumed that the bug, was clear based on
the list of possible return values for each function.
As an example, in qede_parse_flow_attr() it validates dissector->used_keys,
and if an unsupported FLOW_DISSECTOR_KEY_* is set, then ede_parse_flow_attr()
returns -EOPNOTSUPP, which is returned to qede_add_tc_flower_fltr(),
and only check for non-zero, and since -EOPNOTSUPP is non zero,
then it returns -EINVAL. So if you try to match on a vlan tag,
then FLOW_DISSECTOR_KEY_VLAN would be set, and cause a -EOPNOTSUPP
to be returned, which then gets converted into a -EINVAL.
All drivers generally returns -EOPNOTSUPP in their used_keys checks, and
this driver clearly intended to do that as well.
The -EINVAL override was introduced in the same commit as the above check,
so it was broken from the start.
Another example is 319a1d19471e (blamed in 4th patch), Jiri added
a call to flow_action_basic_hw_stats_types_check() across multiple drivers,
and since -EINVAL was returned only a few lines above, then he assumed
that he could just return -EOPNOTSUPP, but that return value gets overruled
into a -EINVAL. It is clear from the commit that Jiri intended to return
-EOPNOTSUPP, but this part of the driver didn't follow the principle of
least astonishment, so that function could only fail with -EINVAL.
I think it's a bug, when another error code is returned than the one that
was clearly intended, but it's properly a low impact one.
> Also, if you do end posting a v2, blamed, is misspelt several
> times in commit messages.
Sorry about that, will fix that if a v2 turns out to be needed.
--
Best regards
Asbjørn Sloth Tønnesen
Network Engineer
Fiberby - AS42541
next prev parent reply other threads:[~2024-04-27 12:58 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 9:12 [PATCH net 0/4] net: qede: avoid overruling error codes Asbjørn Sloth Tønnesen
2024-04-26 9:12 ` [PATCH net 1/4] net: qede: sanitize 'rc' in qede_add_tc_flower_fltr() Asbjørn Sloth Tønnesen
2024-04-27 17:37 ` Simon Horman
2024-04-26 9:12 ` [PATCH net 2/4] net: qede: use return from qede_parse_flow_attr() for flower Asbjørn Sloth Tønnesen
2024-04-27 17:37 ` Simon Horman
2024-04-26 9:12 ` [PATCH net 3/4] net: qede: use return from qede_parse_flow_attr() for flow_spec Asbjørn Sloth Tønnesen
2024-04-27 17:37 ` Simon Horman
2024-04-26 9:12 ` [PATCH net 4/4] net: qede: use return from qede_parse_actions() Asbjørn Sloth Tønnesen
2024-04-27 17:38 ` Simon Horman
2024-04-27 11:48 ` [PATCH net 0/4] net: qede: avoid overruling error codes Simon Horman
2024-04-27 12:58 ` Asbjørn Sloth Tønnesen [this message]
2024-04-27 17:36 ` Simon Horman
2024-04-29 9:10 ` patchwork-bot+netdevbpf
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