linux-kernel - Re: mm: zswap: fix crypto_free_acomp deadlock in zswap_cpu_comp

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Message-ID: <Z75tg3wXoDnGtLis@gondor.apana.org.au>
Date: Wed, 26 Feb 2025 09:25:23 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: Yosry Ahmed <yosry.ahmed@...ux.dev>
Cc: syzbot <syzbot+1a517ccfcbc6a7ab0f82@...kaller.appspotmail.com>,
	davem@...emloft.net, linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org
Subject: Re: mm: zswap: fix crypto_free_acomp deadlock in zswap_cpu_comp_dead

On Tue, Feb 25, 2025 at 01:43:41PM +0000, Yosry Ahmed wrote:
>
> Interesting, it's weird that crypto_free_acomp() allocates memory. Do you have the specific call path?

crypto_free_acomp does not allocate memory.  However, it takes
the same mutex that is also taken on the allocation path.

The specific call path can be seen in the original report:

https://syzkaller.appspot.com/bug?extid=1a517ccfcbc6a7ab0f82

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt