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Mon, 02 Nov 2026 06:12:29 -0800 (PST) Received: from x1e ([196.189.89.249]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4abf751c2d2sm301441565e9.15.2026.11.02.06.12.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Nov 2026 06:12:29 -0800 (PST) From: Maritu Hone To: vireshk@kernel.org Cc: johan@kernel.org, elder@kernel.org, gregkh@linuxfoundation.org, greybus-dev@lists.linaro.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, outreachy@lists.linux.dev, Maritu Hone Subject: [PATCH] staging: greybus: fw-management: validate firmware_tag is NUL-terminated Date: Mon, 2 Nov 2026 17:12:21 +0300 Message-ID: <20261102141221.87646-1-marehone12@gmail.com> X-Mailer: git-send-email 2.43.0 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit fw_mgmt_ioctl() copies struct fw_mgmt_ioc_get_backend_version, struct fw_mgmt_ioc_intf_load_and_validate and struct fw_mgmt_ioc_backend_fw_update directly from userspace via copy_from_user(). Each of these contains a fixed-size firmware_tag[GB_FIRMWARE_U_TAG_MAX_SIZE] array that is never checked for NUL-termination before being used. While the array is eventually copied into a Greybus request via strscpy_pad(), which safely bounds its read and always NUL-terminates its destination, three error paths print the original, unterminated userspace buffer directly with "%s": fw_mgmt_backend_fw_version_operation(): dev_err(..., "failed to get version of %s backend firmware (%d)\n", fw_info->firmware_tag, ret); dev_err(..., "Firmware with tag %s is not supported by Interface\n", fw_info->firmware_tag); fw_mgmt_backend_fw_update_operation(): dev_err(..., "backend %s firmware update request failed (%d)\n", tag, ret); If a caller supplies exactly GB_FIRMWARE_U_TAG_MAX_SIZE non-NUL bytes, "%s" has no terminator inside the array and reads past it into adjacent kernel stack memory until it happens to find a zero byte, leaking that memory into dmesg. Reject the ioctl up front when firmware_tag is not NUL-terminated, mirroring the existing check already used for the equivalent Greybus-module-supplied field in fw_download_find_firmware(). Fixes: 013e66537273 ("greybus: fw-management: Add firmware-management protocol driver") Signed-off-by: Maritu Hone --- drivers/staging/greybus/fw-management.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/drivers/staging/greybus/fw-management.c b/drivers/staging/greybus/fw-management.c index 5d01da6b6eb9..2ee609dd67fb 100644 --- a/drivers/staging/greybus/fw-management.c +++ b/drivers/staging/greybus/fw-management.c @@ -419,6 +419,11 @@ static int fw_mgmt_ioctl(struct fw_mgmt *fw_mgmt, unsigned int cmd, sizeof(backend_fw_info))) return -EFAULT; + if (strnlen(backend_fw_info.firmware_tag, + GB_FIRMWARE_U_TAG_MAX_SIZE) == + GB_FIRMWARE_U_TAG_MAX_SIZE) + return -EINVAL; + ret = fw_mgmt_backend_fw_version_operation(fw_mgmt, &backend_fw_info); if (ret) @@ -433,6 +438,11 @@ static int fw_mgmt_ioctl(struct fw_mgmt *fw_mgmt, unsigned int cmd, if (copy_from_user(&intf_load, buf, sizeof(intf_load))) return -EFAULT; + if (strnlen(intf_load.firmware_tag, + GB_FIRMWARE_U_TAG_MAX_SIZE) == + GB_FIRMWARE_U_TAG_MAX_SIZE) + return -EINVAL; + ret = fw_mgmt_load_and_validate_operation(fw_mgmt, intf_load.load_method, intf_load.firmware_tag); if (ret) @@ -457,6 +467,11 @@ static int fw_mgmt_ioctl(struct fw_mgmt *fw_mgmt, unsigned int cmd, sizeof(backend_update))) return -EFAULT; + if (strnlen(backend_update.firmware_tag, + GB_FIRMWARE_U_TAG_MAX_SIZE) == + GB_FIRMWARE_U_TAG_MAX_SIZE) + return -EINVAL; + ret = fw_mgmt_backend_fw_update_operation(fw_mgmt, backend_update.firmware_tag); if (ret) -- 2.43.0