crypto: seqiv - Do not use req->iv after crypto_aead_encrypt

As soon as crypto_aead_encrypt is called, the underlying request
may be freed by an asynchronous completion.  Thus dereferencing
req->iv after it returns is invalid.

Instead of checking req->iv against info, create a new variable
unaligned_info and use it for that purpose instead.

Fixes: 0a27032 ("[CRYPTO] seqiv: Add Sequence Number IV Generator")
Reported-by: Xiumei Mu <xmu@redhat.com>
Reported-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Author: herbertx

crypto/seqiv.c

@@ -50,6 +50,7 @@ static int seqiv_aead_encrypt(struct aead_request *req)
 	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
 	struct aead_request *subreq = aead_request_ctx(req);
 	crypto_completion_t compl;
+	bool unaligned_info;
 	void *data;
 	u8 *info;
 	unsigned int ivsize = 8;
@@ -68,8 +69,9 @@ static int seqiv_aead_encrypt(struct aead_request *req)
 		memcpy_sglist(req->dst, req->src,
 			      req->assoclen + req->cryptlen);
 
-	if (unlikely(!IS_ALIGNED((unsigned long)info,
-				 crypto_aead_alignmask(geniv) + 1))) {
+	unaligned_info = !IS_ALIGNED((unsigned long)info,
+				     crypto_aead_alignmask(geniv) + 1);
+	if (unlikely(unaligned_info)) {
 		info = kmemdup(req->iv, ivsize, req->base.flags &
 			       CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
 			       GFP_ATOMIC);
@@ -89,7 +91,7 @@ static int seqiv_aead_encrypt(struct aead_request *req)
 	scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
 
 	err = crypto_aead_encrypt(subreq);
-	if (unlikely(info != req->iv))
+	if (unlikely(unaligned_info))
 		seqiv_aead_encrypt_complete2(req, err);
 	return err;
 }