From: Zijun Hu <quic_zijuhu@xxxxxxxxxxx> API of_device_uevent_modalias() makes uevent "MODALIAS=ITS_VALUE" in two steps, namely, produces "MODALIAS=" with add_uevent_var() fistly, then remainning "ITS_VALUE" with of_modalias() finally, and that may result in various wrong uevents as explained below: "MODALIAS=\0" // @env->buf is full after the 1st step. "MODALIAS=ITS_\0" // @env->buf is not enough during 2nd step. "MODALIAS=ITS_VAR=VAR_VALUE\0" // another uevent "VAR=VAR_VALUE" comes. The API depends on uevent internal design, so is not good practice as well. Fix by: 1) Respin the callee of_modalias() with new prototype which is friendly with its callers. 2) Invoke add_uevent_var() to make the whole MODALIAS uevent. 3) Adapt new of_modalias() for its other callers. BTW, there are no external callers of of_modalias() now. Closes: https://lore.kernel.org/all/CAL_JsqL+CRmCQMzcF4-A-PRBrCsfK8nduJtOO=RrsDtCUUR7og@xxxxxxxxxxxxxx Signed-off-by: Zijun Hu <quic_zijuhu@xxxxxxxxxxx> --- drivers/of/device.c | 39 +++++++------------- drivers/of/module.c | 103 +++++++++++++++++++++++++++++++--------------------- include/linux/of.h | 5 +-- 3 files changed, 78 insertions(+), 69 deletions(-) diff --git a/drivers/of/device.c b/drivers/of/device.c index f24c19e7aba8e01656f503ae328a4e08aab5a5f3..6355707c200da9ced354132528adbcce24121247 100644 --- a/drivers/of/device.c +++ b/drivers/of/device.c @@ -195,19 +195,18 @@ EXPORT_SYMBOL(of_device_get_match_data); ssize_t of_device_modalias(struct device *dev, char *str, ssize_t len) { ssize_t sl; + char *ptr __free(kfree) = NULL; if (!dev || !dev->of_node || dev->of_node_reused) return -ENODEV; - sl = of_modalias(dev->of_node, str, len - 2); - if (sl < 0) - return sl; - if (sl > len - 2) + ptr = of_modalias(dev->of_node, &sl); + if (IS_ERR(ptr)) + return PTR_ERR(no_free_ptr(ptr)); + if (sl + 2 > len) return -ENOMEM; - str[sl++] = '\n'; - str[sl] = 0; - return sl; + return snprintf(str, len, "%s\n", ptr); } EXPORT_SYMBOL_GPL(of_device_modalias); @@ -256,30 +255,20 @@ EXPORT_SYMBOL_GPL(of_device_uevent); int of_device_uevent_modalias(const struct device *dev, struct kobj_uevent_env *env) { - int sl; - int pos; + int ret; + char *ptr; if ((!dev) || (!dev->of_node) || dev->of_node_reused) return -ENODEV; - /* Devicetree modalias is tricky, we add it in 2 steps */ - if (add_uevent_var(env, "MODALIAS=")) - return -ENOMEM; + ptr = of_modalias(dev->of_node, NULL); + if (IS_ERR(ptr)) + return PTR_ERR(ptr); - /* - * @env->buflen is pointing to the char after '\0' now - * override the '\0' to save MODALIAS value. - */ - pos = env->buflen - 1; - sl = of_modalias(dev->of_node, &env->buf[pos], - sizeof(env->buf) - pos); - if (sl < 0) - return sl; - if (sl >= (sizeof(env->buf) - pos)) - return -ENOMEM; - env->buflen = pos + sl + 1; + ret = add_uevent_var(env, "MODALIAS=%s", ptr); - return 0; + kfree(ptr); + return ret; } EXPORT_SYMBOL_GPL(of_device_uevent_modalias); diff --git a/drivers/of/module.c b/drivers/of/module.c index 1e735fc130ad3ea9046f08bfab2cc9a07914e633..03a2b1b381e5b353b6699dac183c03186afb0486 100644 --- a/drivers/of/module.c +++ b/drivers/of/module.c @@ -8,71 +8,92 @@ #include <linux/slab.h> #include <linux/string.h> -ssize_t of_modalias(const struct device_node *np, char *str, ssize_t len) +/* + * of_modalias - get MODALIAS string value for a OF device node + * @np: the OF device node + * @lenp: MODALIAS string length returned if set, exclude '\0' + * + * This function gets MODALIAS value for a device node. + * + * Returns MODALIAS string on success, or ERR_PTR() on error. + * + * Note: please kfree successful return value afer using it. + */ +char *of_modalias(const struct device_node *np, ssize_t *lenp) { const char *compat; char *c; struct property *p; ssize_t csize; ssize_t tsize; + char *str = NULL; + ssize_t len = 0; + ssize_t pos = 0; + int counting = 1; + + if (lenp) + *lenp = 0; /* - * Prevent a kernel oops in vsnprintf() -- it only allows passing a - * NULL ptr when the length is also 0. Also filter out the negative - * lengths... + * Two cycles controlled by @counting, the fist cycle counts + * chars, the second saves chars. */ - if ((len > 0 && !str) || len < 0) - return -EINVAL; + do { + /* Name & Type */ + /* %p eats all alphanum characters, so %c must be used here */ + csize = snprintf(str + pos, len - pos, "of:N%pOFn%c%s", np, 'T', + of_node_get_device_type(np)); + if (counting) + tsize = csize; + else + pos += csize; - /* Name & Type */ - /* %p eats all alphanum characters, so %c must be used here */ - csize = snprintf(str, len, "of:N%pOFn%c%s", np, 'T', - of_node_get_device_type(np)); - tsize = csize; - if (csize >= len) - csize = len > 0 ? len - 1 : 0; - len -= csize; - str += csize; + of_property_for_each_string(np, "compatible", p, compat) { + csize = snprintf(str + pos, len - pos, "C%s", compat); + if (counting) { + tsize += csize; + continue; + } - of_property_for_each_string(np, "compatible", p, compat) { - csize = snprintf(str, len, "C%s", compat); - tsize += csize; - if (csize >= len) - continue; - for (c = str; c; ) { - c = strchr(c, ' '); - if (c) - *c++ = '_'; + for (c = str + pos; c; ) { + c = strchr(c, ' '); + if (c) + *c++ = '_'; + } + pos += csize; } - len -= csize; - str += csize; - } - return tsize; + if (counting) { + /* Include '\0' of MODALIAS string. */ + len = tsize + 1; + /* MODALIAS value is too long */ + if (unlikely(len > 2048)) + return ERR_PTR(-EINVAL); + + str = kmalloc(len, GFP_KERNEL); + if (!str) + return ERR_PTR(-ENOMEM); + } + + } while (counting--); + + if (lenp) + *lenp = tsize; + return str; } int of_request_module(const struct device_node *np) { char *str; - ssize_t size; int ret; if (!np) return -ENODEV; - size = of_modalias(np, NULL, 0); - if (size < 0) - return size; - - /* Reserve an additional byte for the trailing '\0' */ - size++; - - str = kmalloc(size, GFP_KERNEL); - if (!str) - return -ENOMEM; + str = of_modalias(np, NULL); + if (IS_ERR(str)) + return PTR_ERR(str); - of_modalias(np, str, size); - str[size - 1] = '\0'; ret = request_module(str); kfree(str); diff --git a/include/linux/of.h b/include/linux/of.h index 7b0da8d352dffd8b872998903282119b6164a5bc..2fcc12de4a9178276a24cd4d6c975495b9eb04a2 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -382,7 +382,7 @@ extern int of_count_phandle_with_args(const struct device_node *np, const char *list_name, const char *cells_name); /* module functions */ -extern ssize_t of_modalias(const struct device_node *np, char *str, ssize_t len); +char *of_modalias(const struct device_node *np, ssize_t *lenp); extern int of_request_module(const struct device_node *np); /* phandle iterator functions */ @@ -762,8 +762,7 @@ static inline int of_count_phandle_with_args(const struct device_node *np, return -ENOSYS; } -static inline ssize_t of_modalias(const struct device_node *np, char *str, - ssize_t len) +static inline char *of_modalias(const struct device_node *np, ssize_t *lenp) { return -ENODEV; } -- 2.34.1
