From: Sumeet Pawnikar Date: Sun, 7 Dec 2025 15:15:48 +0000 (+0530) Subject: powercap: fix sscanf() error return value handling X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=efc4c35b741af973de90f6826bf35d3b3ac36bf1;p=thirdparty%2Flinux.git powercap: fix sscanf() error return value handling Fix inconsistent error handling for sscanf() return value check. Implicit boolean conversion is used instead of explicit return value checks. The code checks if (!sscanf(...)) which is incorrect because: 1. sscanf returns the number of successfully parsed items 2. On success, it returns 1 (one item passed) 3. On failure, it returns 0 or EOF 4. The check 'if (!sscanf(...))' is wrong because it treats success (1) as failure All occurrences of sscanf() now uses explicit return value check. With this behavior it returns '-EINVAL' when parsing fails (returns 0 or EOF), and continues when parsing succeeds (returns 1). Signed-off-by: Sumeet Pawnikar [ rjw: Subject and changelog edits ] Link: https://patch.msgid.link/20251207151549.202452-1-sumeet4linux@gmail.com Signed-off-by: Rafael J. Wysocki --- diff --git a/drivers/powercap/powercap_sys.c b/drivers/powercap/powercap_sys.c index d14b36b75189..1ff369880beb 100644 --- a/drivers/powercap/powercap_sys.c +++ b/drivers/powercap/powercap_sys.c @@ -68,7 +68,7 @@ static ssize_t show_constraint_##_attr(struct device *dev, \ int id; \ struct powercap_zone_constraint *pconst;\ \ - if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) \ + if (sscanf(dev_attr->attr.name, "constraint_%d_", &id) != 1) \ return -EINVAL; \ if (id >= power_zone->const_id_cnt) \ return -EINVAL; \ @@ -93,7 +93,7 @@ static ssize_t store_constraint_##_attr(struct device *dev,\ int id; \ struct powercap_zone_constraint *pconst;\ \ - if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) \ + if (sscanf(dev_attr->attr.name, "constraint_%d_", &id) != 1) \ return -EINVAL; \ if (id >= power_zone->const_id_cnt) \ return -EINVAL; \ @@ -162,7 +162,7 @@ static ssize_t show_constraint_name(struct device *dev, ssize_t len = -ENODATA; struct powercap_zone_constraint *pconst; - if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) + if (sscanf(dev_attr->attr.name, "constraint_%d_", &id) != 1) return -EINVAL; if (id >= power_zone->const_id_cnt) return -EINVAL;