Fix compile warning with GCC 11.

When configured with strict warnings, GCC 11 complains about a possible
stringop-translation:

Config:

/usr/bin/perl ./Configure enable-asan enable-ubsan enable-zlib-dynamic \
enable-unit-test enable-md2 enable-rc5 enable-buildtest-c++ \
enable-weak-ssl-ciphers enable-ssl3 enable-ssl3-method enable-fips -w \
--strict-warnings

Warning:

crypto/evp/ctrl_params_translate.c: In function 'fix_rsa_pss_saltlen':
crypto/evp/ctrl_params_translate.c:1356:13: error: 'strncpy' specified bound 50 equals destination size [-Werror=stringop-truncation]
 1356 |             strncpy(ctx->name_buf, str_value_map[i].ptr, sizeof(ctx->name_buf));
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix by copying one byte less than the buffer size.  We anyway overwrite the
last byte.

Signed-off-by: Juergen Christ <jchrist@linux.ibm.com>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15993)

diff --git a/crypto/evp/ctrl_params_translate.c b/crypto/evp/ctrl_params_translate.c
index c532e57f8f6da976bc0edadb62f543a92bafff74..4ea17380af94eaeddf5275b813f6f105d1b44599 100644 (file)
--- a/crypto/evp/ctrl_params_translate.c
+++ b/crypto/evp/ctrl_params_translate.c
@@ -1353,8 +1353,8 @@ static int fix_rsa_pss_saltlen(enum state state,
         if (i == OSSL_NELEM(str_value_map)) {
             BIO_snprintf(ctx->name_buf, sizeof(ctx->name_buf), "%d", ctx->p1);
         } else {
-            strncpy(ctx->name_buf, str_value_map[i].ptr, sizeof(ctx->name_buf));
             /* This won't truncate but it will quiet static analysers */
+            strncpy(ctx->name_buf, str_value_map[i].ptr, sizeof(ctx->name_buf) - 1);
             ctx->name_buf[sizeof(ctx->name_buf) - 1] = '\0';
         }
         ctx->p2 = ctx->name_buf;