From patchwork Wed Oct 11 22:20:10 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Justin Stitt X-Patchwork-Id: 13418017 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0DEA7249E1 for ; Wed, 11 Oct 2023 22:20:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="t/xRp+KT" Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E2E5CAF for ; Wed, 11 Oct 2023 15:20:13 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-5a22eb73cb3so5044747b3.3 for ; Wed, 11 Oct 2023 15:20:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1697062813; x=1697667613; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=+Z96mQSNwBQxmdfHTfVSOBB7yU8CSx8L0b3jKxEJcSo=; b=t/xRp+KTkHXq8Zld68JmaIzatv4ge2hi3hStZct8v/vgd5cKy+VFYjtbiq32MFWdQr xT+YGEQvzbhLbQPgd/xjR10kHAnLFNnPSXND3Oc6RR2ChgZrvNjYay3ABUQWubbYrnkU WFX9M7ybiEY1cmr3U29xAk9dR9EpQ0AjtWOHv3e2tts4/VSjOTILeifRdAJwI6hsBrK9 hXPvfy7sclOVx4Zm/yYoCtbfvuheL7UaRJCUWGED/PFEpgxeSkPXl/h1Pi1fcY89oZY9 tjNfSiunez2m5mur/NMFXbIw9Bs0QTD8piG1hJNZmtrKWkqEEmp4/fr5Lc6w+kXnuJPH 7P+w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1697062813; x=1697667613; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=+Z96mQSNwBQxmdfHTfVSOBB7yU8CSx8L0b3jKxEJcSo=; b=MQ44dQk+p+WSjcc8FuyfuLGc3EjiWQ+iCp1qQFc0T1hfMPKxh9Mt4n+IDc2/oLIF4O U48YKBPNjf42f7TIF1SVDNHobVSrLedto1cyJHrypAhsOuCZaitfSkgzYDR/sj/M9DAS IsnbSP8W/1EYAS+i5w5S4oJtUWYNZFw31Jd9yMkchqoDdgVCKMaYI7B8tZ5+S8/SvLAA nnc/TSKKi7vVOQlENUwFP/bU5QIVzlEBBVMJI4kCYQ0Exx8MGC8Zu81sgroQdv50na/L JA4TOPMYSzjojLL6XyIXlYDaBfgBlfESs+yBRmkKMoWvjLFxv2yJsx22wqIDPEdnRF9X wQ4A== X-Gm-Message-State: AOJu0YzNt4aNOgJb0hpZ0q0pupub94i+6+8XlstiA8f5ZDw8cJ2FghWr SdeQ82hTObdoV3GpccRCpFGtvDIdVPPjYZLHJQ== X-Google-Smtp-Source: AGHT+IGd5Zu1czxmjeL92aynbzUWAyCyWUMLzy4yM/u30YUbNTfHqpMJqGR4vyeCgOUkYHcW+xZmuu5thXi55bh27Q== X-Received: from jstitt-linux1.c.googlers.com ([fda3:e722:ac3:cc00:2b:ff92:c0a8:23b5]) (user=justinstitt job=sendgmr) by 2002:a05:6902:a89:b0:d9a:5e10:c34d with SMTP id cd9-20020a0569020a8900b00d9a5e10c34dmr122450ybb.11.1697062813111; Wed, 11 Oct 2023 15:20:13 -0700 (PDT) Date: Wed, 11 Oct 2023 22:20:10 +0000 Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-B4-Tracking: v=1; b=H4sIAJkfJ2UC/x2NQQrCMBBFr1Jm7UAm1oVeRUQ0+aYDkraTtCild 7d18eC/zX8LFZii0KVZyDBr0T5vIoeGQvfICaxxc/LOH8WJcKmWw/DlaDrDCmdURu1g+xjffdL AI+LOPeI5JQ7sReLp3HonaGl7Hgwv/fyr19u6/gDruxsxhQAAAA== X-Developer-Key: i=justinstitt@google.com; a=ed25519; pk=tC3hNkJQTpNX/gLKxTNQKDmiQl6QjBNCGKJINqAdJsE= X-Developer-Signature: v=1; a=ed25519-sha256; t=1697062812; l=3458; i=justinstitt@google.com; s=20230717; h=from:subject:message-id; bh=fcCFEgzIEgjdRagOjBJiBiruUTRZY6XKVFUfoSVmwHk=; b=aYtaA7N793tac2LBAe3z26VJ83HnPC3XYeXKcuGTOdnHD3nZAM+z+JKRjHuFt+Elo3vhm+wOG /yIou6N7Ph6BRinJjrPjxnxkxoggxVG9baAO0ZIlWMuNMFUZlG1R4cS X-Mailer: b4 0.12.3 Message-ID: <20231011-strncpy-drivers-net-ethernet-qlogic-qed-qed_debug-c-v1-1-60c9ca2d54a2@google.com> Subject: [PATCH] qed: replace uses of strncpy From: Justin Stitt To: Ariel Elior , Manish Chopra , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Kees Cook , Justin Stitt X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. This patch eliminates three uses of strncpy(): Firstly, `dest` is expected to be NUL-terminated which is evident by the manual setting of a NUL-byte at size - 1. For this use specifically, strscpy() is a viable replacement due to the fact that it guarantees NUL-termination on the destination buffer. The next two changes utilizes snprintf() to make the copying behavior more obvious. Previously, strncpy() was used to overwrite the first 3 characters of mem_name and type_name by setting a length argument less than the size of the buffers themselves. This enables, in a roundabout way, creating a string like "ASD_BIG_RAM" or "ASD_RAM". Let's just use snprintf() with a precision specifier to hold the name prefix to exactly 3 characters long. To be clear, there are no buffer overread bugs in the current code as the sizes and offsets are carefully managed such that buffers are NUL-terminated. However, with these changes, the code is now more robust and less ambiguous (and hopefully easier to read). 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 Cc: Kees Cook Signed-off-by: Justin Stitt --- Note: build-tested only. Found with: $ rg "strncpy\(" --- drivers/net/ethernet/qlogic/qed/qed_debug.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2 change-id: 20231011-strncpy-drivers-net-ethernet-qlogic-qed-qed_debug-c-211d594201e4 Best regards, -- Justin Stitt diff --git a/drivers/net/ethernet/qlogic/qed/qed_debug.c b/drivers/net/ethernet/qlogic/qed/qed_debug.c index cdcead614e9f..0a4fd1b04353 100644 --- a/drivers/net/ethernet/qlogic/qed/qed_debug.c +++ b/drivers/net/ethernet/qlogic/qed/qed_debug.c @@ -3192,8 +3192,8 @@ static u32 qed_grc_dump_big_ram(struct qed_hwfn *p_hwfn, { struct dbg_tools_data *dev_data = &p_hwfn->dbg_info; u32 block_size, ram_size, offset = 0, reg_val, i; - char mem_name[12] = "???_BIG_RAM"; - char type_name[8] = "???_RAM"; + char mem_name[12]; + char type_name[8]; struct big_ram_defs *big_ram; big_ram = &s_big_ram_defs[big_ram_id]; @@ -3204,8 +3204,11 @@ static u32 qed_grc_dump_big_ram(struct qed_hwfn *p_hwfn, BIT(big_ram->is_256b_bit_offset[dev_data->chip_id]) ? 256 : 128; - strncpy(type_name, big_ram->instance_name, BIG_RAM_NAME_LEN); - strncpy(mem_name, big_ram->instance_name, BIG_RAM_NAME_LEN); + snprintf(mem_name, sizeof(mem_name), "%.*s_BIG_RAM", + BIG_RAM_NAME_LEN, big_ram->instance_name); + + snprintf(type_name, sizeof(type_name), "%.*s_RAM", + BIG_RAM_NAME_LEN, big_ram->instance_name); /* Dump memory header */ offset += qed_grc_dump_mem_hdr(p_hwfn, @@ -6359,8 +6362,7 @@ static void qed_read_str_from_buf(void *buf, u32 *offset, u32 size, char *dest) { const char *source_str = &((const char *)buf)[*offset]; - strncpy(dest, source_str, size); - dest[size - 1] = '\0'; + strscpy(dest, source_str, size); *offset += size; }