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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Tadeusz Struk <tadeusz.struk@linaro.org>,
        Eric Biggers <ebiggers@google.com>,
        Herbert Xu <herbert@gondor.apana.org.au>
Subject: [PATCH 5.17 0163/1126] crypto: rsa-pkcs1pad - fix buffer overread in pkcs1pad_verify_complete()
Date:   Tue,  5 Apr 2022 09:15:10 +0200
Message-Id: <20220405070412.379079190@linuxfoundation.org>
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From: Eric Biggers <ebiggers@google.com>

commit a24611ea356c7f3f0ec926da11b9482ac1f414fd upstream.

Before checking whether the expected digest_info is present, we need to
check that there are enough bytes remaining.

Fixes: a49de377e051 ("crypto: Add hash param to pkcs1pad")
Cc: <stable@vger.kernel.org> # v4.6+
Cc: Tadeusz Struk <tadeusz.struk@linaro.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 crypto/rsa-pkcs1pad.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/crypto/rsa-pkcs1pad.c
+++ b/crypto/rsa-pkcs1pad.c
@@ -476,6 +476,8 @@ static int pkcs1pad_verify_complete(stru
 	pos++;
 
 	if (digest_info) {
+		if (digest_info->size > dst_len - pos)
+			goto done;
 		if (crypto_memneq(out_buf + pos, digest_info->data,
 				  digest_info->size))
 			goto done;