linux-kernel - [PATCH] crypto: ccree: Fix use after free in cc_cipher

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Date:   Thu,  3 Mar 2022 10:23:37 +0800
From:   Jianglei Nie <niejianglei2021@....com>
To:     gilad@...yossef.com, herbert@...dor.apana.org.au,
        davem@...emloft.net
Cc:     linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jianglei Nie <niejianglei2021@....com>
Subject: [PATCH] crypto: ccree: Fix use after free in cc_cipher_exit()

kfree_sensitive(ctx_p->user.key) will free the ctx_p->user.key. But
ctx_p->user.key is still used in the next line, which will lead to a
use after free.

We can call kfree_sensitive() after dev_dbg() to avoid the uaf.

Signed-off-by: Jianglei Nie <niejianglei2021@....com>
---
 drivers/crypto/ccree/cc_cipher.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/crypto/ccree/cc_cipher.c b/drivers/crypto/ccree/cc_cipher.c
index 78833491f534..309da6334a0a 100644
--- a/drivers/crypto/ccree/cc_cipher.c
+++ b/drivers/crypto/ccree/cc_cipher.c
@@ -257,8 +257,8 @@ static void cc_cipher_exit(struct crypto_tfm *tfm)
 		&ctx_p->user.key_dma_addr);
 
 	/* Free key buffer in context */
-	kfree_sensitive(ctx_p->user.key);
 	dev_dbg(dev, "Free key buffer in context. key=@%p\n", ctx_p->user.key);
+	kfree_sensitive(ctx_p->user.key);
 }
 
 struct tdes_keys {
-- 
2.25.1