linux-kernel - [PATCH] crypto: ahash - Fix infinite recursion in ahash_def

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Message-ID: <aE-Y7VzdJTDJHsy_@gondor.apana.org.au>
Date: Mon, 16 Jun 2025 12:09:17 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: Eric Biggers <ebiggers@...nel.org>
Cc: linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org,
	linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
	sparclinux@...r.kernel.org, x86@...nel.org, ardb@...nel.org,
	Jason@...c4.com, torvalds@...ux-foundation.org
Subject: [PATCH] crypto: ahash - Fix infinite recursion in ahash_def_finup

On Sat, Jun 14, 2025 at 08:18:07PM -0700, Eric Biggers wrote:
>
> Even with your patch applied, it overflows the stack when running the crypto
> self-tests, apparently due to crypto/ahash.c calling into itself recursively:

Thanks for the report.  This driver doesn't provide a finup function
which triggered a bug in the default finup implementation:

---8<---
Invoke the final function directly in the default finup implementation
since crypto_ahash_final is now just a wrapper around finup.

Reported-by: Eric Biggers <ebiggers@...nel.org>
Fixes: 9d7a0ab1c753 ("crypto: ahash - Handle partial blocks in API")
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

diff --git a/crypto/ahash.c b/crypto/ahash.c
index bd9e49950201..3878b4da3cfd 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -603,12 +603,14 @@ static void ahash_def_finup_done2(void *data, int err)
 
 static int ahash_def_finup_finish1(struct ahash_request *req, int err)
 {
+	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
+
 	if (err)
 		goto out;
 
 	req->base.complete = ahash_def_finup_done2;
 
-	err = crypto_ahash_final(req);
+	err = crypto_ahash_alg(tfm)->final(req);
 	if (err == -EINPROGRESS || err == -EBUSY)
 		return err;
 
-- 
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