netdev - RE: [PATCH net-next v2 1/9] devlink: use min_t to calculate data

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <d561b49935234451ac062f9f12c50e83@AcuMS.aculab.com>
Date:   Thu, 24 Nov 2022 21:53:09 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Jacob Keller' <jacob.e.keller@...el.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     Jiri Pirko <jiri@...dia.com>, Jakub Kicinski <kuba@...nel.org>
Subject: RE: [PATCH net-next v2 1/9] devlink: use min_t to calculate data_size

From: Jacob Keller
> Sent: 23 November 2022 20:38
> 
> The calculation for the data_size in the devlink_nl_read_snapshot_fill
> function uses an if statement that is better expressed using the min_t
> macro.

There ought to be a 'duck shoot' arranged for all uses of min_t().
I was testing a patch (I might submit next week) that relaxes the
checks in min() so that it doesn't error a lot of valid cases.
In particular a positive integer constant can always be cast to (int)
and the compare will DTRT.

I found things like min_t(u32, u32_length, u64_limit) where
you really don't want to mask the limit down.
There are also the min_t(u8, ...) and min_t(u16, ...).

...
> +		data_size = min_t(u32, end_offset - curr_offset,
> +				  DEVLINK_REGION_READ_CHUNK_SIZE);

Here I think both xxx_offset are u32 - so the CHUNK_SIZE
constant probably needs a U suffix.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)