Commit 9a8d289f authored Jul 28, 2014 by Mimi Zohar

ima: fix ima_alloc_atfm()



The patch 3bcced39: "ima: use ahash API for file hash
calculation" from Feb 26, 2014, leads to the following static checker
warning:

security/integrity/ima/ima_crypto.c:204 ima_alloc_atfm()
         error: buffer overflow 'hash_algo_name' 17 <= 17

Unlike shash tfm memory, which is allocated on initialization, the
ahash tfm memory allocation is deferred until needed.

This patch fixes the case where ima_ahash_tfm has not yet been
allocated and the file's signature/hash xattr contains an invalid hash
algorithm.  Although we can not verify the xattr, we still need to
measure the file.  Use the default IMA hash algorithm.

Changelog:
- set valid algo before testing tfm - based on Dmitry's comment

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>

parent fbff6610

security/integrity/ima/ima_crypto.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -200,7 +200,10 @@ static struct crypto_ahash *ima_alloc_atfm(enum hash_algo algo)
		struct crypto_ahash *tfm = ima_ahash_tfm;
		int rc;

		if ((algo != ima_hash_algo && algo < HASH_ALGO__LAST) \|\| !tfm) {
		if (algo < 0 \|\| algo >= HASH_ALGO__LAST)
		algo = ima_hash_algo;

		if (algo != ima_hash_algo \|\| !tfm) {
		tfm = crypto_alloc_ahash(hash_algo_name[algo], 0, 0);
		if (!IS_ERR(tfm)) {
		if (algo == ima_hash_algo)