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 1b0f76ba3eb5ee898d1f1f86e594e44d99c9b8bd..59260aefed2807d948c03faf78ccc661616a2eb1 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 09be909a6a1aadf7ab1b19ed9c9488e5352c82dd..548b302c6c6a00a1ff51011123f1373d6c870dc2 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] != ')')