linux-kernel - Re: [PATCH V2] crypto: Mark intermediary memory as clean

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Message-ID: <tencent_50604BE61B0A2525BA07BB9033239E401B08@qq.com>
Date: Mon, 18 Aug 2025 20:17:17 +0800
From: Edward Adam Davis <eadavis@...com>
To: herbert@...dor.apana.org.au
Cc: davem@...emloft.net,
	eadavis@...com,
	linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	syzbot+e8bcd7ee3db6cb5cb875@...kaller.appspotmail.com,
	syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH V2] crypto: Mark intermediary memory as clean

On Sun, 17 Aug 2025 19:40:56 +0800, Herbert Xu wrote:
> > diff --git a/crypto/jitterentropy-kcapi.c b/crypto/jitterentropy-kcapi.c
> > index 1266eb790708..4020a6e41b0e 100644
> > --- a/crypto/jitterentropy-kcapi.c
> > +++ b/crypto/jitterentropy-kcapi.c
> > @@ -117,6 +117,7 @@ int jent_hash_time(void *hash_state, __u64 time, u8 *addtl,
> >  		pr_warn_ratelimited("Unexpected digest size\n");
> >  		return -EINVAL;
> >  	}
> > +	kmsan_unpoison_memory(intermediary, SHA3_256_DIGEST_SIZE);
> 
> Please change SHA3_256_DIGEST_SIZE to sizeof(intermediary).
Why?
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?

BR,
Edward