Linux cryptographic layer development
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From: Stephan Mueller <smueller@chronox.de>
To: Edward Adam Davis <eadavis@qq.com>
Cc: herbert@gondor.apana.org.au, davem@davemloft.net, eadavis@qq.com,
	linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
	syzbot+e8bcd7ee3db6cb5cb875@syzkaller.appspotmail.com,
	syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH V2] crypto: Mark intermediary memory as clean
Date: Mon, 18 Aug 2025 15:13:47 +0200	[thread overview]
Message-ID: <7740195.jRhZ6ZUK3Y@tauon> (raw)
In-Reply-To: <tencent_F8BAB8BB23338A9E2C1B4F4BD11BD9252E08@qq.com>

Am Montag, 18. August 2025, 14:43:36 Mitteleuropäische Sommerzeit schrieb 
Edward Adam Davis:

Hi Edward,

> On Mon, 18 Aug 2025 20:30:29 +0800, Herbert Xu wrote:
> > Their values are equal, so why use sizeof to calculate?
> > Similarly, "if (sizeof(intermediary) !=
> > crypto_shash_digestsize(desc->tfm)) {", why not just use
> > SHA3_256_DIGEST_SIZE?
> 
> Hi Stephan Mueller, can you explain it?

If the question is why using sizeof(intermediary) instead of 
SHA3_256_DIGEST_SIZE, then it is very trivial: I always want to avoid any kind 
of double work. If for any reason the buffer size of intermediary changes, the 
current code only requires *one* location to fix it.

When changing the branching condition to use SHA3_256_DIGEST_SIZE, we would 
have to change *two* locations which is more error-prone than to change one. 
This approach is my common coding style to try to minimize the possibilities 
where inconsistencies can occur.

Ciao
Stephan



  reply	other threads:[~2025-08-18 13:19 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-08  8:07 [syzbot] [crypto?] KMSAN: kernel-infoleak in rng_recvmsg syzbot
2025-08-09  9:59 ` [PATCH] crypto: Prevent " Edward Adam Davis
2025-08-16  9:17   ` Herbert Xu
2025-08-17  8:51     ` Herbert Xu
2025-08-17 10:59       ` [PATCH V2] crypto: Mark intermediary memory as clean Edward Adam Davis
2025-08-17 11:40         ` Herbert Xu
2025-08-18 12:17           ` Edward Adam Davis
2025-08-18 12:30             ` Herbert Xu
2025-08-18 12:43               ` Edward Adam Davis
2025-08-18 13:13                 ` Stephan Mueller [this message]
2025-08-18 13:24                   ` [PATCH V3] " Edward Adam Davis
2025-08-18 13:32                     ` Stephan Mueller
2025-08-30  8:45                     ` Herbert Xu
2025-08-26 13:51     ` [PATCH] crypto: Prevent kernel-infoleak in rng_recvmsg Ard Biesheuvel
2025-08-26 16:58       ` Kees Cook

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