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Commit 8c32c516 authored by Herbert Xu's avatar Herbert Xu
Browse files

crypto: hash - Zap unaligned buffers 



Some unaligned buffers on the stack weren't zapped properly which
may cause secret data to be leaked.  This patch fixes them by doing
a zero memset.

It is also possible for us to place random kernel stack contents
in the digest buffer if a digest operation fails.  This is fixed
by only copying if the operation succeeded.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 500b3e3c

crypto/ahash.c

+1 −2
Original line number Diff line number Diff line
@@ -152,8 +152,7 @@ static int ahash_setkey_unaligned(struct crypto_ahash *tfm, const u8 *key, 
	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);

	memcpy(alignbuffer, key, keylen);

	ret = ahash->setkey(tfm, alignbuffer, keylen);

	memset(alignbuffer, 0, keylen);

	kfree(buffer);

	kzfree(buffer);

	return ret;

}

crypto/shash.c

+11 −3
Original line number Diff line number Diff line
@@ -45,8 +45,7 @@ static int shash_setkey_unaligned(struct crypto_shash *tfm, const u8 *key, 
	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);

	memcpy(alignbuffer, key, keylen);

	err = shash->setkey(tfm, alignbuffer, keylen);

	memset(alignbuffer, 0, keylen);

	kfree(buffer);

	kzfree(buffer);

	return err;

}
@@ -79,13 +78,16 @@ static int shash_update_unaligned(struct shash_desc *desc, const u8 *data, 
				     ((unsigned long)data & alignmask);

	u8 buf[shash_align_buffer_size(unaligned_len, alignmask)]

		__attribute__ ((aligned));

	int err;



	if (unaligned_len > len)

		unaligned_len = len;



	memcpy(buf, data, unaligned_len);

	err = shash->update(desc, buf, unaligned_len);

	memset(buf, 0, unaligned_len);



	return shash->update(desc, buf, unaligned_len) ?:

	return err ?:

	       shash->update(desc, data + unaligned_len, len - unaligned_len);

}
@@ -114,7 +116,13 @@ static int shash_final_unaligned(struct shash_desc *desc, u8 *out) 
	int err;



	err = shash->final(desc, buf);

	if (err)

		goto out;



	memcpy(out, buf, ds);



out:

	memset(buf, 0, ds);

	return err;

}