2022-12-28 01:49:19

by Yang Yang

Subject: [PATCH linux-next] ecryptfs: crypto: use strscpy() to instead of strncpy()

From: Xu Panda <[email protected]>

The implementation of strscpy() is more robust and safer.
That's now the recommended way to copy NUL-terminated strings.

Signed-off-by: Xu Panda <[email protected]>
Signed-off-by: Yang Yang <[email protected]>
---
fs/ecryptfs/crypto.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 03263ebcccc6..c618a6878584 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1630,9 +1630,8 @@ ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
goto out;
}
mutex_init(&tmp_tfm->key_tfm_mutex);
- strncpy(tmp_tfm->cipher_name, cipher_name,
- ECRYPTFS_MAX_CIPHER_NAME_SIZE);
- tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
+ strscpy(tmp_tfm->cipher_name, cipher_name,
+ ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1);
tmp_tfm->key_size = key_size;
rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
tmp_tfm->cipher_name,
--
2.15.2

2022-12-29 21:11:43

by Eric Biggers

Subject: Re: [PATCH linux-next] ecryptfs: crypto: use strscpy() to instead of strncpy()

On Wed, Dec 28, 2022 at 09:36:54AM +0800, [email protected] wrote:
> From: Xu Panda <[email protected]>
>
> The implementation of strscpy() is more robust and safer.
> That's now the recommended way to copy NUL-terminated strings.

Unlike strncpy(), strscpy() does not initialize the full destination array, so
it is unsafe in some situations, such as initializing structures that are then
copied to userspace or to disk. Please include an actual explanation for why
this patch is correct.

- Eric