crypto: lrw,xts - Replace strlcpy with strscpy

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().

Direct replacement is safe here since return value of -errno
is used to check for truncation instead of sizeof(dest).

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/lrw.c b/crypto/lrw.c
index 1b0f76b..59260ae 100644 (file)
--- a/crypto/lrw.c
+++ b/crypto/lrw.c
@@ -357,10 +357,10 @@ static int lrw_create(struct crypto_template *tmpl, struct rtattr **tb)
         * cipher name.
         */
        if (!strncmp(cipher_name, "ecb(", 4)) {
-               unsigned len;
+               int len;
 
-               len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
-               if (len < 2 || len >= sizeof(ecb_name))
+               len = strscpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
+               if (len < 2)
                        goto err_free_inst;
 
                if (ecb_name[len - 1] != ')')

diff --git a/crypto/xts.c b/crypto/xts.c
index 09be909..548b302 100644 (file)
--- a/crypto/xts.c
+++ b/crypto/xts.c
@@ -396,10 +396,10 @@ static int xts_create(struct crypto_template *tmpl, struct rtattr **tb)
         * cipher name.
         */
        if (!strncmp(cipher_name, "ecb(", 4)) {
-               unsigned len;
+               int len;
 
-               len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
-               if (len < 2 || len >= sizeof(ctx->name))
+               len = strscpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
+               if (len < 2)
                        goto err_free_inst;
 
                if (ctx->name[len - 1] != ')')