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b=H4sIAOrKNmUC/x2NQQqDQAwAvyI5N7Crpbr9SilFYlZzMJVkkRbx7 116mMNcZg5wNmGHe3OA8S4ub60SLw3QMurMKFN1aEPbxQp6MaXti5PJzuboXQqoXJAKra91FEX CnOIQ8rUPdEtQU5txls9/83ie5w+JKpDSdgAAAA== X-Developer-Key: i=justinstitt@google.com; a=ed25519; pk=tC3hNkJQTpNX/gLKxTNQKDmiQl6QjBNCGKJINqAdJsE= X-Developer-Signature: v=1; a=ed25519-sha256; t=1698089708; l=2146; i=justinstitt@google.com; s=20230717; h=from:subject:message-id; bh=2i13pUNg5jdPNAKizwFkDgsEeFj20v602g+x3gcL7mQ=; b=ky84JixLgjvwMNGmiy2NSzwFeHDXPKLBEYdk92wBMLHMD7ib2CZNN4xkwdsRAgNnU8scCvJZ6 grVyjyo+v9WDPSdC5jcZNOWZG0aCmk3iFtMEQDho7OnlVjudLIvWdr8 X-Mailer: b4 0.12.3 Message-ID: <20231023-strncpy-drivers-s390-net-ctcm_main-c-v1-1-265db6e78165@google.com> Subject: [PATCH] s390/ctcm: replace deprecated strncpy with strscpy From: Justin Stitt To: Alexandra Winter , Wenjia Zhang , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle Cc: linux-s390@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Justin Stitt X-Spam-Status: No, score=-8.4 required=5.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on agentk.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (agentk.vger.email [0.0.0.0]); Mon, 23 Oct 2023 12:35:28 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1780576136949085275 X-GMAIL-MSGID: 1780576136949085275 strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. We expect chid to be NUL-terminated based on its use with format strings: CTCM_DBF_TEXT_(SETUP, CTC_DBF_INFO, "%s(%s) %s", CTCM_FUNTAIL, chid, ok ? "OK" : "failed"); Moreover, NUL-padding is not required as it is _only_ used in this one instance with a format string. Considering the above, a suitable replacement is `strscpy` [2] due to the fact that it guarantees NUL-termination on the destination buffer without unnecessarily NUL-padding. We can also drop the +1 from chid's declaration as we no longer need to be cautious about leaving a spot for a NUL-byte. Let's use the more idiomatic strscpy usage of (dest, src, sizeof(dest)) as this more closely ties the destination buffer to the length. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt Reviewed-by: Thorsten Winkler Tested-by: Thorsten Winkler Reviewed-by: Kees Cook --- Note: build-tested only. Found with: $ rg "strncpy\(" --- drivers/s390/net/ctcm_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- base-commit: 9c5d00cb7b6bbc5a7965d9ab7d223b5402d1f02c change-id: 20231023-strncpy-drivers-s390-net-ctcm_main-c-f9180f470c69 Best regards, -- Justin Stitt diff --git a/drivers/s390/net/ctcm_main.c b/drivers/s390/net/ctcm_main.c index 6faf27136024..ac15d7c2b200 100644 --- a/drivers/s390/net/ctcm_main.c +++ b/drivers/s390/net/ctcm_main.c @@ -200,13 +200,13 @@ static void channel_free(struct channel *ch) static void channel_remove(struct channel *ch) { struct channel **c = &channels; - char chid[CTCM_ID_SIZE+1]; + char chid[CTCM_ID_SIZE]; int ok = 0; if (ch == NULL) return; else - strncpy(chid, ch->id, CTCM_ID_SIZE); + strscpy(chid, ch->id, sizeof(chid)); channel_free(ch); while (*c) {