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From:   Shreyansh Chouhan <chouhan.shreyansh630@gmail.com>
To:     herbert@gondor.apana.org.au, davem@davemloft.net,
        tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org,
        hpa@zytor.com, ardb@kernel.org
Cc:     Shreyansh Chouhan <chouhan.shreyansh630@gmail.com>,
        linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
        syzbot+20191dc583eff8602d2d@syzkaller.appspotmail.com
Subject: [PATCH] crypto: xts_crypt() return if walk.nbytes is 0
Date:   Mon,  9 Aug 2021 19:40:27 +0530
Message-Id: <20210809141027.860850-1-chouhan.shreyansh630@gmail.com>
In-Reply-To: <YQ0Qm+Xs1g/7Eant@fedora>
References: <YQ0Qm+Xs1g/7Eant@fedora>
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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>
---
 arch/x86/crypto/aesni-intel_glue.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c
index 388643ca2177..ec6eac57c493 100644
--- 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_request *req, bool encrypt)
 		return -EINVAL;
 
 	err = skcipher_walk_virt(&walk, req, false);
-	if (err)
+	if (err || !walk.nbytes)
 		return err;
 
 	if (unlikely(tail > 0 && walk.nbytes < walk.total)) {
-- 
2.31.1