On 12/27/2022 10:46 AM, Roberto Sassu wrote:

From: Roberto Sassu roberto.sassu@huawei.com

Commit ac4e97abce9b8 ("scatterlist: sg_set_buf() argument must be in linear mapping") checks that both the signature and the digest reside in the linear mapping area.

However, more recently commit ba14a194a434c ("fork: Add generic vmalloced stack support"), made it possible to move the stack in the vmalloc area, which is not contiguous, and thus not suitable for sg_set_buf() which needs adjacent pages.

Always make a copy of the signature and digest in the same buffer used to store the key and its parameters, and pass them to sg_set_buf(). Prefer it to conditionally doing the copy if necessary, to keep the code simple. The buffer allocated with kmalloc() is in the linear mapping area.

Cc: stable@vger.kernel.org # 4.9.x Fixes: ba14a194a434 ("fork: Add generic vmalloced stack support") Link: https://lore.kernel.org/linux-integrity/Y4pIpxbjBdajymBJ@sol.localdomain/ Suggested-by: Eric Biggers ebiggers@kernel.org Signed-off-by: Roberto Sassu roberto.sassu@huawei.com

---

crypto/asymmetric_keys/public_key.c | 39 ++++++++++++++++------------- 1 file changed, 22 insertions(+), 17 deletions(-)

diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c index 2f8352e88860..a479e32cb280 100644 --- a/crypto/asymmetric_keys/public_key.c +++ b/crypto/asymmetric_keys/public_key.c @@ -360,9 +360,10 @@ int public_key_verify_signature(const struct public_key *pkey, struct crypto_wait cwait; struct crypto_akcipher *tfm; struct akcipher_request *req;

• struct scatterlist src_sg[2];

• struct scatterlist src_sg; char alg_name[CRYPTO_MAX_ALG_NAME];

• char *key, *ptr;

• char *buf, *ptr;
• size_t buf_len; int ret;

pr_devel("==>%s()\n", __func__); @@ -400,34 +401,38 @@ int public_key_verify_signature(const struct public_key *pkey, if (!req) goto error_free_tfm;

• key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,

•       GFP_KERNEL);
  

• if (!key)

• buf_len = max_t(size_t, pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,

• 	sig->s_size + sig->digest_size);
  

• buf = kmalloc(buf_len, GFP_KERNEL);
• if (!buf) goto error_free_req;

• memcpy(key, pkey->key, pkey->keylen);
• ptr = key + pkey->keylen;

• memcpy(buf, pkey->key, pkey->keylen);
• ptr = buf + pkey->keylen; ptr = pkey_pack_u32(ptr, pkey->algo); ptr = pkey_pack_u32(ptr, pkey->paramlen); memcpy(ptr, pkey->params, pkey->paramlen);

if (pkey->key_is_private)

• ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
  

• ret = crypto_akcipher_set_priv_key(tfm, buf, pkey->keylen);
  

  else

• ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
  

• ret = crypto_akcipher_set_pub_key(tfm, buf, pkey->keylen);
  

  if (ret)

• goto error_free_key;
  

• goto error_free_buf;
  

if (strcmp(pkey->pkey_algo, "sm2") == 0 && sig->data_size) { ret = cert_sig_digest_update(sig, tfm); if (ret)

• 	goto error_free_key;
  

• 	goto error_free_buf;
  

  }

• sg_init_table(src_sg, 2);
• sg_set_buf(&src_sg[0], sig->s, sig->s_size);
• sg_set_buf(&src_sg[1], sig->digest, sig->digest_size);
• akcipher_request_set_crypt(req, src_sg, NULL, sig->s_size,

• memcpy(buf, sig->s, sig->s_size);
• memcpy(buf + sig->s_size, sig->digest, sig->digest_size);
• sg_init_table(&src_sg, 1);
• sg_set_buf(&src_sg, buf, sig->s_size + sig->digest_size);

Ops, didn't commit the changes. Will send a new version soon.

Roberto

• akcipher_request_set_crypt(req, &src_sg, NULL, sig->s_size, sig->digest_size); crypto_init_wait(&cwait); akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |

@@ -435,8 +440,8 @@ int public_key_verify_signature(const struct public_key *pkey, crypto_req_done, &cwait); ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait); -error_free_key:

• kfree(key);

+error_free_buf:

• kfree(buf); error_free_req: akcipher_request_free(req); error_free_tfm: