From: Chenyuan Yang chenyuan0y@gmail.com
[ Upstream commit a99b598d836c9c6411110c70a2da134c78d96e67 ]
The returned value, pfsm->miscdev.name, from devm_kasprintf() could be NULL. A pointer check is added to prevent potential NULL pointer dereference. This is similar to the fix in commit 3027e7b15b02 ("ice: Fix some null pointer dereference issues in ice_ptp.c").
This issue is found by our static analysis tool.
Signed-off-by: Chenyuan Yang chenyuan0y@gmail.com Link: https://lore.kernel.org/r/20250311010511.1028269-1-chenyuan0y@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org ---
**YES**
This commit should be backported to stable kernel trees. Here's my detailed analysis:
## Analysis
### 1. Bug Fix Nature This commit fixes a clear NULL pointer dereference vulnerability. The `devm_kasprintf()` function can return NULL on memory allocation failure, and the code was not checking this return value before using `pfsm->miscdev.name`. This would lead to a NULL pointer dereference when `misc_register(&pfsm->miscdev)` is called at line 302.
### 2. Code Analysis Looking at the specific changes in `drivers/misc/tps6594-pfsm.c`:
**Before the fix (lines 282-283):** ```c pfsm->miscdev.name = devm_kasprintf(dev, GFP_KERNEL, "pfsm-%ld-0x%02x", tps->chip_id, tps->reg); ```
**After the fix (lines 282-286):** ```c pfsm->miscdev.name = devm_kasprintf(dev, GFP_KERNEL, "pfsm-%ld-0x%02x", tps->chip_id, tps->reg); +if (!pfsm->miscdev.name) + return -ENOMEM; ```
The fix adds essential NULL pointer checking that prevents potential kernel crashes.
### 3. Comparison with Similar Commits This fix follows the exact same pattern as the reference commits marked as "Backport Status: YES":
- **Similar Commit #1 (ipmi)**: Same issue with `devm_kasprintf()` not being checked - **Similar Commit #2 (mfd: tps6594)**: Same issue, even in the same TPS6594 subsystem - **Similar Commit #4 (ice)**: Same issue, explicitly referenced in the commit message
All these similar commits were deemed suitable for backporting because they fix the same fundamental issue.
### 4. Risk Assessment - **Minimal risk**: The fix is a simple 2-line addition that only adds error checking - **No side effects**: The change doesn't alter functionality, only prevents crashes - **Contained scope**: Only affects the TPS6594 PFSM driver initialization path - **No architectural changes**: Doesn't modify any interfaces or major logic
### 5. Stability Criteria Met - ✅ **Important bug fix**: Prevents kernel NULL pointer dereference crashes - ✅ **Minimal and contained**: Only 2 lines added for error checking - ✅ **Low regression risk**: Cannot introduce new issues, only prevents crashes - ✅ **Clear fix**: Addresses a well-defined problem with obvious solution
### 6. Driver Context The TPS6594 PFSM driver was introduced in kernel v6.10, making it a relatively recent addition. The driver handles power management for TI PMIC devices, making reliability crucial for system stability.
### 7. Static Analysis Tool Finding The commit message mentions this was found by static analysis, which indicates it's a real potential issue that could manifest under memory pressure conditions.
This commit clearly meets all the criteria for stable tree backporting: it's a small, contained fix for an important potential crash bug with minimal risk of regression.
drivers/misc/tps6594-pfsm.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/misc/tps6594-pfsm.c b/drivers/misc/tps6594-pfsm.c index 0a24ce44cc37c..6db1c9d48f8fc 100644 --- a/drivers/misc/tps6594-pfsm.c +++ b/drivers/misc/tps6594-pfsm.c @@ -281,6 +281,9 @@ static int tps6594_pfsm_probe(struct platform_device *pdev) pfsm->miscdev.minor = MISC_DYNAMIC_MINOR; pfsm->miscdev.name = devm_kasprintf(dev, GFP_KERNEL, "pfsm-%ld-0x%02x", tps->chip_id, tps->reg); + if (!pfsm->miscdev.name) + return -ENOMEM; + pfsm->miscdev.fops = &tps6594_pfsm_fops; pfsm->miscdev.parent = dev->parent; pfsm->chip_id = tps->chip_id;