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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,
        syzbot+20191dc583eff8602d2d@syzkaller.appspotmail.com,
        Shreyansh Chouhan <chouhan.shreyansh630@gmail.com>,
        Herbert Xu <herbert@gondor.apana.org.au>
Subject: [PATCH 5.14 167/172] crypto: aesni - xts_crypt() return if walk.nbytes is 0
Date:   Mon,  4 Oct 2021 14:53:37 +0200
Message-Id: <20211004125050.365000165@linuxfoundation.org>
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From: Shreyansh Chouhan <chouhan.shreyansh630@gmail.com>

commit 72ff2bf04db2a48840df93a461b7115900f46c05 upstream.

xts_crypt() code doesn't call kernel_fpu_end() after calling
kernel_fpu_begin() if walk.nbytes is 0. The correct behavior should be
not calling kernel_fpu_begin() if walk.nbytes is 0.

Reported-by: syzbot+20191dc583eff8602d2d@syzkaller.appspotmail.com
Signed-off-by: Shreyansh Chouhan <chouhan.shreyansh630@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/crypto/aesni-intel_glue.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/crypto/aesni-intel_glue.c
+++ b/arch/x86/crypto/aesni-intel_glue.c
@@ -849,7 +849,7 @@ static int xts_crypt(struct skcipher_req
 		return -EINVAL;
 
 	err = skcipher_walk_virt(&walk, req, false);
-	if (err)
+	if (!walk.nbytes)
 		return err;
 
 	if (unlikely(tail > 0 && walk.nbytes < walk.total)) {