From mboxrd@z Thu Jan 1 00:00:00 1970 From: tycho@tycho.ws (Tycho Andersen) Date: Mon, 12 Mar 2018 22:29:06 -0600 Subject: [PATCH 1/2] big key: get rid of stack array allocation Message-ID: <20180313042907.29598-1-tycho@tycho.ws> To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org We're interested in getting rid of all of the stack allocated arrays in the kernel [1]. This patch removes one in keys by switching to malloc/free. Note that we use kzalloc, to avoid leaking the nonce. I'm not sure this is really necessary, but extra paranoia seems prudent. Manually tested using the program from the add_key man page to trigger big_key. [1]: https://lkml.org/lkml/2018/3/7/621 Signed-off-by: Tycho Andersen CC: David Howells CC: James Morris CC: "Serge E. Hallyn" CC: Jason A. Donenfeld --- security/keys/big_key.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/security/keys/big_key.c b/security/keys/big_key.c index fa728f662a6f..70f9f785c59d 100644 --- a/security/keys/big_key.c +++ b/security/keys/big_key.c @@ -108,13 +108,18 @@ static int big_key_crypt(enum big_key_op op, struct big_key_buf *buf, size_t dat * an .update function, so there's no chance we'll wind up reusing the * key to encrypt updated data. Simply put: one key, one encryption. */ - u8 zero_nonce[crypto_aead_ivsize(big_key_aead)]; + u8 *zero_nonce; + + zero_nonce = kzalloc(crypto_aead_ivsize(big_key_aead), GFP_KERNEL); + if (!zero_nonce) + return -ENOMEM; aead_req = aead_request_alloc(big_key_aead, GFP_KERNEL); - if (!aead_req) + if (!aead_req) { + kfree(zero_nonce); return -ENOMEM; + } - memset(zero_nonce, 0, sizeof(zero_nonce)); aead_request_set_crypt(aead_req, buf->sg, buf->sg, datalen, zero_nonce); aead_request_set_callback(aead_req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL); aead_request_set_ad(aead_req, 0); @@ -131,6 +136,7 @@ static int big_key_crypt(enum big_key_op op, struct big_key_buf *buf, size_t dat error: mutex_unlock(&big_key_aead_lock); aead_request_free(aead_req); + kzfree(zero_nonce); return ret; } -- 2.15.1 -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html