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b=H4sIAJ/tAWUC/42NQQqDMBBFryKz7hSTSEO76j2KC5uMcaAamUioi Hdvai/QzYf3+by/QSJhSnCrNhDKnDhOBfSpAjd0UyBkXxh0rU19VRrTIpObV/TCmSRhWQnyPPI vvO8a+zTWmt5DkcxCPb+Pg0dbeOC0RFmPv6y+7d/qrFChc42h2ivX0eUeYgwvOrs4Qrvv+wdjT 2SwzQAAAA== X-Developer-Key: i=justinstitt@google.com; a=ed25519; pk=tC3hNkJQTpNX/gLKxTNQKDmiQl6QjBNCGKJINqAdJsE= X-Developer-Signature: v=1; a=ed25519-sha256; t=1694625185; l=2941; i=justinstitt@google.com; s=20230717; h=from:subject:message-id; bh=FDmfRrAoS66Rbbc25XcYmCZjZlwmE2RZWNS4Ok/5S0k=; b=E2uwLU3YiJUf5HxNMMXdX8SkcKNpi07uqk0WHe0v9DIfto0Upi/ltttoRVU6rUSIFiESIwDYh nM6tsROJ+DDDhGrrDYB1vZqhyjHrUVXazVor5thhRkpcNSlrEop/x7D X-Mailer: b4 0.12.3 Message-ID: <20230913-strncpy-drivers-char-ipmi-ipmi-v2-1-e3bc0f6e599f@google.com> Subject: [PATCH v2] ipmi: refactor deprecated strncpy From: Justin Stitt To: Corey Minyard Cc: openipmi-developer@lists.sourceforge.net, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Kees Cook , Justin Stitt 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 (groat.vger.email [0.0.0.0]); Wed, 13 Sep 2023 10:13:18 -0700 (PDT) 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 groat.vger.email X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1776952085306615278 X-GMAIL-MSGID: 1776952085306615278 `strncpy` is deprecated for use on NUL-terminated destination strings [1]. In this case, strncpy is being used specifically for its NUL-padding behavior (and has been commented as such). Moreover, the destination string is not required to be NUL-terminated [2]. We can use a more robust and less ambiguous interface in `memcpy_and_pad` which makes the code more readable and even eliminates the need for that comment. Let's also use `strnlen` instead of `strlen()` with an upper-bounds check as this is intrinsically a part of `strnlen`. Also included in this patch is a simple 1:1 change of `strncpy` to `strscpy` for ipmi_ssif.c. If NUL-padding is wanted here as well then we should opt again for `strscpy_pad`. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://lore.kernel.org/all/ZQEADYBl0uZ1nX60@mail.minyard.net/ [2] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Cc: Kees Cook Signed-off-by: Justin Stitt --- Changes in v2: - use memcpy_and_pad (thanks Corey) - Link to v1: https://lore.kernel.org/r/20230912-strncpy-drivers-char-ipmi-ipmi-v1-1-cc43e0d1cae6@google.com --- drivers/char/ipmi/ipmi_msghandler.c | 11 +++-------- drivers/char/ipmi/ipmi_ssif.c | 2 +- 2 files changed, 4 insertions(+), 9 deletions(-) --- base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c change-id: 20230912-strncpy-drivers-char-ipmi-ipmi-dda47b3773fd Best regards, -- Justin Stitt diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c index 186f1fee7534..d6f14279684d 100644 --- a/drivers/char/ipmi/ipmi_msghandler.c +++ b/drivers/char/ipmi/ipmi_msghandler.c @@ -5377,20 +5377,15 @@ static void send_panic_events(struct ipmi_smi *intf, char *str) j = 0; while (*p) { - int size = strlen(p); + int size = strnlen(p, 11); - if (size > 11) - size = 11; data[0] = 0; data[1] = 0; data[2] = 0xf0; /* OEM event without timestamp. */ data[3] = intf->addrinfo[0].address; data[4] = j++; /* sequence # */ - /* - * Always give 11 bytes, so strncpy will fill - * it with zeroes for me. - */ - strncpy(data+5, p, 11); + + memcpy_and_pad(data+5, 11, p, size, '\0'); p += size; ipmi_panic_request_and_wait(intf, &addr, &msg); diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c index 3b921c78ba08..edcb83765dce 100644 --- a/drivers/char/ipmi/ipmi_ssif.c +++ b/drivers/char/ipmi/ipmi_ssif.c @@ -1940,7 +1940,7 @@ static int new_ssif_client(int addr, char *adapter_name, } } - strncpy(addr_info->binfo.type, DEVICE_NAME, + strscpy(addr_info->binfo.type, DEVICE_NAME, sizeof(addr_info->binfo.type)); addr_info->binfo.addr = addr; addr_info->binfo.platform_data = addr_info;