From 9510aa4aebf32678884f55ae251e54012a354ed1 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Alice=20=E2=9C=A8=F0=9F=8C=99=20Luna?= Date: Sat, 22 Aug 2026 16:26:42 +0200 Subject: [PATCH] Use sysfs_emit and field width specifier '*' This fixes the build due to strncpy being removed from the kernel 7.2 and also makes the code more readable, since the handling of buffer overflows id done by sysfs_emit. Note that the documentation about reading attributes says: > New implementations of show() methods should only use sysfs_emit() > or sysfs_emit_at() when formatting the value to be returned to user space. See: https://docs.kernel.org/filesystems/sysfs.html#reading-writing-attribute-data from kernel 7.2.0, last revised 16 August 2011. This change also uses the field width specifier '*' for add_uevent_var calls. --- ddcci/ddcci.c | 153 +++++++++++++++++--------------------------------- 1 file changed, 50 insertions(+), 103 deletions(-) diff --git a/ddcci/ddcci.c b/ddcci/ddcci.c index 6b41eab..76a1cd3 100644 --- a/ddcci/ddcci.c +++ b/ddcci/ddcci.c @@ -735,154 +735,101 @@ static ssize_t ddcci_attr_capabilities_show(struct device *dev, char *buf) { struct ddcci_device *device = ddcci_verify_device(dev); - ssize_t ret = -ENOENT; - size_t len; if (likely(device != NULL)) { - len = device->capabilities_len; - if (unlikely(len > PAGE_SIZE)) - len = PAGE_SIZE; - if (len == 0) { - ret = len; - } else { - memcpy(buf, device->capabilities, len); - if (likely(len < PAGE_SIZE)) { - buf[len] = '\n'; - ret = len+1; - } - } - } + if (device->capabilities_len == 0) + return 0; - return ret; + return sysfs_emit(buf, "%.*s\n", (int)device->capabilities_len, device->capabilities); + } + return -ENOENT; } static ssize_t ddcci_attr_prot_show(struct device *dev, struct device_attribute *attr, char *buf) { struct ddcci_device *device = ddcci_verify_device(dev); - ssize_t ret = -ENOENT; - size_t len; if (likely(device != NULL)) { - len = strnlen(device->prot, sizeof(device->prot)); - strncpy(buf, device->prot, PAGE_SIZE); - if (len == 0) { - ret = len; - } else if (likely(len < PAGE_SIZE)) { - buf[len] = '\n'; - ret = len+1; - } else { - ret = PAGE_SIZE; - } + if (device->prot[0] == '\0') + return 0; + + return sysfs_emit(buf, "%.*s\n", (int)sizeof(device->prot), device->prot); } - return ret; + return -ENOENT; } static ssize_t ddcci_attr_type_show(struct device *dev, struct device_attribute *attr, char *buf) { struct ddcci_device *device = ddcci_verify_device(dev); - ssize_t ret = -ENOENT; - size_t len; if (likely(device != NULL)) { - len = strnlen(device->type, sizeof(device->type)); - strncpy(buf, device->type, PAGE_SIZE); - if (len == 0) { - ret = len; - } else if (likely(len < PAGE_SIZE)) { - buf[len] = '\n'; - ret = len+1; - } else { - ret = PAGE_SIZE; - } + if (device->type[0] == '\0') + return 0; + + return sysfs_emit(buf, "%.*s\n", (int)sizeof(device->type), device->type); } - return ret; + return -ENOENT; } static ssize_t ddcci_attr_model_show(struct device *dev, struct device_attribute *attr, char *buf) { struct ddcci_device *device = ddcci_verify_device(dev); - ssize_t ret = -ENOENT; - size_t len; if (likely(device != NULL)) { - len = strnlen(device->model, sizeof(device->model)); - strncpy(buf, device->model, PAGE_SIZE); - if (len == 0) { - ret = len; - } else if (likely(len < PAGE_SIZE)) { - buf[len] = '\n'; - ret = len+1; - } else { - ret = PAGE_SIZE; - } + if (device->model[0] == '\0') + return 0; + + return sysfs_emit(buf, "%.*s\n", (int)sizeof(device->model), device->model); } - return ret; + return -ENOENT; } static ssize_t ddcci_attr_vendor_show(struct device *dev, struct device_attribute *attr, char *buf) { struct ddcci_device *device = ddcci_verify_device(dev); - ssize_t ret = -ENOENT; - size_t len; if (likely(device != NULL)) { - len = strnlen(device->vendor, sizeof(device->vendor)); - strncpy(buf, device->vendor, PAGE_SIZE); - if (len == 0) { - ret = len; - } else if (likely(len < PAGE_SIZE)) { - buf[len] = '\n'; - ret = len+1; - } else { - ret = PAGE_SIZE; - } + if (device->vendor[0] == '\0') + return 0; + + return sysfs_emit(buf, "%.*s\n", (int)sizeof(device->vendor), device->vendor); } - return ret; + return -ENOENT; } static ssize_t ddcci_attr_module_show(struct device *dev, struct device_attribute *attr, char *buf) { struct ddcci_device *device = ddcci_verify_device(dev); - ssize_t ret = -ENOENT; - size_t len; if (likely(device != NULL)) { - len = strnlen(device->module, sizeof(device->module)); - strncpy(buf, device->module, PAGE_SIZE); - if (len == 0) { - ret = len; - } else if (likely(len < PAGE_SIZE)) { - buf[len] = '\n'; - ret = len+1; - } else { - ret = PAGE_SIZE; - } + if (device->module[0] == '\0') + return 0; + + return sysfs_emit(buf, "%.*s\n", (int)sizeof(device->module), device->module); } - return ret; + return -ENOENT; } static ssize_t ddcci_attr_serial_show(struct device *dev, struct device_attribute *attr, char *buf) { struct ddcci_device *device = ddcci_verify_device(dev); - ssize_t ret = -ENOENT; if (likely(device != NULL)) - ret = scnprintf(buf, PAGE_SIZE, "%d\n", device->device_number); + return sysfs_emit(buf, "%d\n", device->device_number); - return ret; + return -ENOENT; } static ssize_t ddcci_attr_modalias_show(struct device *dev, struct device_attribute *attr, char *buf) { struct ddcci_device *device = ddcci_verify_device(dev); - ssize_t ret = -ENOENT; char model[ARRAY_SIZE(device->model)]; char vendor[ARRAY_SIZE(device->model)]; char module[ARRAY_SIZE(device->model)]; @@ -895,16 +842,16 @@ static ssize_t ddcci_attr_modalias_show(struct device *dev, ddcci_modalias_clean(vendor, sizeof(vendor), '_'); ddcci_modalias_clean(module, sizeof(module), '_'); - ret = scnprintf(buf, PAGE_SIZE, "%s%s-%s-%s-%s-%s\n", + return sysfs_emit(buf, "%s%.*s-%.*s-%.*s-%.*s-%.*s\n", DDCCI_MODULE_PREFIX, - device->prot, - device->type, - model, - vendor, - module + (int)sizeof(device->prot), device->prot, + (int)sizeof(device->type), device->type, + (int)sizeof(model), model, + (int)sizeof(vendor), vendor, + (int)sizeof(module), module ); } - return ret; + return -ENOENT; } static DEVICE_ATTR(capabilities, S_IRUGO, ddcci_attr_capabilities_show, NULL); @@ -945,33 +892,33 @@ static int ddcci_device_uevent(CSTRUCT device *dev, struct kobj_uevent_env *env) ddcci_modalias_clean(vendor, sizeof(vendor), '_'); ddcci_modalias_clean(module, sizeof(module), '_'); - if (add_uevent_var(env, "MODALIAS=%s%s-%s-%s-%s-%s", + if (add_uevent_var(env, "MODALIAS=%s%.*s-%.*s-%.*s-%.*s-%.*s", DDCCI_MODULE_PREFIX, - device->prot, - device->type, - model, - vendor, - module + (int)sizeof(device->prot), device->prot, + (int)sizeof(device->type), device->type, + (int)sizeof(model), model, + (int)sizeof(vendor), vendor, + (int)sizeof(module), module )) return -ENOMEM; if (device->prot[0]) - if (add_uevent_var(env, "DDCCI_PROT=%s", device->prot)) + if (add_uevent_var(env, "DDCCI_PROT=%.*s", (int)sizeof(device->prot), device->prot)) return -ENOMEM; if (device->type[0]) - if (add_uevent_var(env, "DDCCI_TYPE=%s", device->type)) + if (add_uevent_var(env, "DDCCI_TYPE=%.*s", (int)sizeof(device->type), device->type)) return -ENOMEM; if (device->model[0]) - if (add_uevent_var(env, "DDCCI_MODEL=%s", device->model)) + if (add_uevent_var(env, "DDCCI_MODEL=%.*s", (int)sizeof(device->model), device->model)) return -ENOMEM; if (device->vendor[0]) { - if (add_uevent_var(env, "DDCCI_VENDOR=%s", device->vendor)) + if (add_uevent_var(env, "DDCCI_VENDOR=%.*s", (int)sizeof(device->vendor), device->vendor)) return -ENOMEM; - if (add_uevent_var(env, "DDCCI_MODULE=%s", device->module)) + if (add_uevent_var(env, "DDCCI_MODULE=%.*s", (int)sizeof(device->module), device->module)) return -ENOMEM; if (add_uevent_var(env, "DDCCI_UNIQ=%d", device->device_number)) -- 2.54.0