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 | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c index 2f8352e88860..ccc091119972 100644 --- a/crypto/asymmetric_keys/public_key.c +++ b/crypto/asymmetric_keys/public_key.c @@ -363,6 +363,7 @@ int public_key_verify_signature(const struct public_key *pkey, struct scatterlist src_sg[2]; char alg_name[CRYPTO_MAX_ALG_NAME]; char *key, *ptr; + u32 key_max_len; int ret;

pr_devel("==>%s()\n", __func__); @@ -400,8 +401,12 @@ 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); + key_max_len = max_t(u32, + pkey->keylen + sizeof(u32) * 2 + pkey->paramlen, + sig->s_size + sig->digest_size); + + /* key is used to store the sig and digest too. */ + key = kmalloc(key_max_len, GFP_KERNEL); if (!key) goto error_free_req;

@@ -424,9 +429,13 @@ int public_key_verify_signature(const struct public_key *pkey, goto error_free_key; }

+ memcpy(key, sig->s, sig->s_size); + memcpy(key + sig->s_size, sig->digest, sig->digest_size); + 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); + /* Cannot use one scatterlist. The first needs to be s->s_size long. */ + sg_set_buf(&src_sg[0], key, sig->s_size); + sg_set_buf(&src_sg[1], key + sig->s_size, sig->digest_size); akcipher_request_set_crypt(req, src_sg, NULL, sig->s_size, sig->digest_size); crypto_init_wait(&cwait);