t)  // garbage comparison
    return -EINVAL;
pconst = &power_zone->constraints[id];  // POTENTIAL OUT-OF-BOUNDS
ACCESS
```

### 3. CLASSIFICATION

This is a **bug fix** that prevents:
- Potential out-of-bounds array access
- Use of uninitialized variable
- Possible kernel crash or memory corruption in edge cases

Not a feature addition, code cleanup, or optimization.

### 4. SCOPE AND RISK ASSESSMENT

- **Lines changed**: 3 lines (identical pattern)
- **Files affected**: 1 file
- **Risk**: Extremely low - the change only makes the check stricter and
  more explicit
- **Could break anything?**: No - the new check `!= 1` is strictly more
  conservative than `!`

### 5. USER IMPACT

The powercap subsystem manages:
- Intel RAPL power capping
- Power domain constraints
- Used by tools like powertop, thermald

While the EOF triggering condition is rare (would require malformed
attribute names), the consequence (OOB access) could be severe.

### 6. STABILITY INDICATORS

- Signed-off by Rafael J. Wysocki (Intel power management maintainer)
- Self-contained fix with no dependencies
- The powercap subsystem has existed since kernel 3.13

### 7. DEPENDENCY CHECK

- No dependencies on other commits
- Simple standalone fix
- Code exists in all active stable trees

## Summary

**What it fixes**: Incorrect sscanf error handling that could allow
execution with uninitialized data, potentially leading to out-of-bounds
array access.

**Why it matters for stable**: While the triggering condition (EOF from
sscanf) is rare, the fix prevents a potential memory safety issue. The
change is trivially correct with zero regression risk.

**Meets stable criteria**:
- ✓ Obviously correct (explicit `!= 1` check is cleaner and more robust)
- ✓ Fixes a real bug (uninitialized variable use, potential OOB access)
- ✓ Small and contained (3 identical one-line changes)
- ✓ No new features
- ✓ No dependencies

**Risk vs benefit**: The benefit (preventing potential memory
corruption) outweighs the near-zero risk of regression.

**YES**

 drivers/powercap/powercap_sys.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

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;
-- 
2.51.0[PATCH AUTOSEL 6.18-5.10] powercap: fix sscanf() error return value handlingSasha Levin <sashal@kernel.org> undefinedpatches@lists.linux.dev, stable@vger.kernel.org undefined undefined undefined undefined undefined undefined