strcpy() is deprecated; use the safer strscpy() and use its return value, the number of bytes copied, instead of calling strlen() on the destination buffer again. String truncation can be ignored since 'derived_buf' is guaranteed to be large enough.
Link: https://github.com/KSPP/linux/issues/88 Signed-off-by: Thorsten Blum <[email protected]> --- Changes in v2: - Revert some changes to include the trailing '\0' even if key_type == 0 since this would change the bytes passed to sha256() (Eric Biggers) - Use strscpy() and its return value instead - Link to v1: https://lore.kernel.org/lkml/[email protected]/ --- security/keys/encrypted-keys/encrypted.c | 21 ++++++++------------- 1 file changed, 8 insertions(+), 13 deletions(-) diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c index 15841466b5d4..94408909f1dd 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 +331,17 @@ 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; + ssize_t len; + derived_buf_len = max(strlen("AUTH_KEY") + 1 + 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); + key_name = key_type ? "AUTH_KEY" : "ENC_KEY"; + len = strscpy(derived_buf, key_name, derived_buf_len); + memcpy(derived_buf + len + 1, master_key, master_keylen); sha256(derived_buf, derived_buf_len, derived_key); kfree_sensitive(derived_buf); return 0; -- 2.51.1
