Determine 'key_name' before allocating memory for 'derived_buf' to only allocate as many bytes as needed. Currently, we potentially allocate one more byte than necessary when 'key_name' is "ENC_KEY".
strcpy() is deprecated and uses an additional strlen() internally; use memcpy() directly to copy 'key_name' since we already know its length and that it is guaranteed to be NUL-terminated. Also reuse 'key_name_len' when copying 'master_key' instead of calling strlen() again. Link: https://github.com/KSPP/linux/issues/88 Signed-off-by: Thorsten Blum <[email protected]> --- security/keys/encrypted-keys/encrypted.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c index 15841466b5d4..b16a5b8b935b 100644 --- a/security/keys/encrypted-keys/encrypted.c +++ b/security/keys/encrypted-keys/encrypted.c @@ -12,6 +12,7 @@ */ #include <linux/uaccess.h> +#include <linux/minmax.h> #include <linux/module.h> #include <linux/init.h> #include <linux/slab.h> @@ -330,23 +331,18 @@ static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, const u8 *master_key, size_t master_keylen) { u8 *derived_buf; - unsigned int derived_buf_len; - - derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; - if (derived_buf_len < HASH_SIZE) - derived_buf_len = HASH_SIZE; + size_t derived_buf_len; + const char *key_name; + size_t key_name_len; + key_name = key_type ? "AUTH_KEY" : "ENC_KEY"; + key_name_len = strlen(key_name) + 1; + derived_buf_len = max(key_name_len + master_keylen, HASH_SIZE); derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); if (!derived_buf) return -ENOMEM; - - if (key_type) - strcpy(derived_buf, "AUTH_KEY"); - else - strcpy(derived_buf, "ENC_KEY"); - - memcpy(derived_buf + strlen(derived_buf) + 1, master_key, - master_keylen); + memcpy(derived_buf, key_name, key_name_len); + memcpy(derived_buf + key_name_len, master_key, master_keylen); sha256(derived_buf, derived_buf_len, derived_key); kfree_sensitive(derived_buf); return 0; -- 2.51.1
