[PATCH] video: fbdev: omapfb: Add missing error check for clk_get()

[PATCH] video: fbdev: omapfb: Add missing error check for clk_get()

[Chen Ni]

The hwa742_init() function did not check the return value of clk_get().
This could lead to dereferencing an error pointer in subsequent clock
operations, potentially causing a kernel crash.

Fix this by adding a missing error check and ensuring proper clock
resource cleanup on failure and driver removal.

Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
---
 drivers/video/fbdev/omap/hwa742.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/video/fbdev/omap/hwa742.c b/drivers/video/fbdev/omap/hwa742.c
index 64e76e1f5388..68a677f824e9 100644
--- a/drivers/video/fbdev/omap/hwa742.c
+++ b/drivers/video/fbdev/omap/hwa742.c
@@ -950,6 +950,8 @@ static int hwa742_init(struct omapfb_device *fbdev, int ext_mode,
 	omapfb_conf = dev_get_platdata(fbdev->dev);
 
 	hwa742.sys_ck = clk_get(NULL, "hwa_sys_ck");
+	if (IS_ERR(hwa742.sys_ck))
+		return PTR_ERR(hwa742.sys_ck);
 
 	spin_lock_init(&hwa742.req_lock);
 
@@ -1028,6 +1030,7 @@ static int hwa742_init(struct omapfb_device *fbdev, int ext_mode,
 err2:
 	hwa742.int_ctrl->cleanup();
 err1:
+	clk_put(hwa742.sys_ck);
 	return r;
 }
 
@@ -1037,6 +1040,7 @@ static void hwa742_cleanup(void)
 	hwa742.extif->cleanup();
 	hwa742.int_ctrl->cleanup();
 	clk_disable_unprepare(hwa742.sys_ck);
+	clk_put(hwa742.sys_ck);
 }
 
 struct lcd_ctrl hwa742_ctrl = {
-- 
2.25.1

Re: [PATCH] video: fbdev: omapfb: Add missing error check for clk_get()

[Helge Deller]

On 3/10/26 09:56, Chen Ni wrote:
> The hwa742_init() function did not check the return value of clk_get().
> This could lead to dereferencing an error pointer in subsequent clock
> operations, potentially causing a kernel crash.
> 
> Fix this by adding a missing error check and ensuring proper clock
> resource cleanup on failure and driver removal.
> 
> Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
> ---
>   drivers/video/fbdev/omap/hwa742.c | 4 ++++
>   1 file changed, 4 insertions(+)

applied.
Thanks!
Helge

Claude review: video: fbdev: omapfb: Add missing error check for clk_get()

[Claude Code Review Bot]

Overall Series Review

Subject: video: fbdev: omapfb: Add missing error check for clk_get()
Author: Chen Ni <nichen@iscas.ac.cn>
Patches: 2
Reviewed: 2026-03-11T13:28:19.231251

---

This is a single-patch series adding a missing error check for `clk_get()` in the OMAP HWA742 fbdev driver. The bug is real — `clk_get()` can return an error pointer, and the current code blindly passes it to `clk_get_rate()`, `clk_prepare_enable()`, etc., which would dereference the error pointer and crash the kernel. The fix is straightforward and mostly correct, though it has one issue with the error path cleanup.

---
Generated by Claude Code Patch Reviewer

Claude review: video: fbdev: omapfb: Add missing error check for clk_get()

[Claude Code Review Bot]

Patch Review

**The IS_ERR check is correct and needed.** The `clk_get()` call at line 952 is indeed unchecked, and adding the check is the right thing to do:

```c
hwa742.sys_ck = clk_get(NULL, "hwa_sys_ck");
+	if (IS_ERR(hwa742.sys_ck))
+		return PTR_ERR(hwa742.sys_ck);
```

This is fine — at this point in `hwa742_init()`, no resources have been acquired yet (the `int_ctrl->init()` and `extif->init()` calls happen later), so returning directly is correct rather than going through the error unwind labels.

**The `clk_put()` in `err1` is problematic.** Looking at the error paths:

```c
err1:
+	clk_put(hwa742.sys_ck);
	return r;
```

The `err1` label is reached from line 956-957:
```c
if ((r = hwa742.int_ctrl->init(fbdev, 1, req_vram)) < 0)
    goto err1;
```

And also falls through from `err2`:
```c
err2:
	hwa742.int_ctrl->cleanup();
err1:
+	clk_put(hwa742.sys_ck);
	return r;
```

Since `clk_get()` succeeded if we reach any of these labels (the IS_ERR check returns early), calling `clk_put()` at `err1` is correct. Similarly, `err3` and `err4` flow through `err2` → `err1`, so all error paths will now properly release the clock. This is actually fine.

**The `clk_put()` in `hwa742_cleanup()` is correct:**

```c
	clk_disable_unprepare(hwa742.sys_ck);
+	clk_put(hwa742.sys_ck);
```

The clock needs to be released on driver cleanup. The ordering (disable/unprepare first, then put) is correct.

**Minor observation:** This driver uses the legacy `clk_get(NULL, ...)` / `clk_put()` API rather than `devm_clk_get()`. Converting to the managed API would be a further improvement but is outside the scope of this fix and would be a separate cleanup patch.

**Overall:** The patch is correct and addresses a real bug. The error handling and cleanup are properly structured. 

Reviewed-by looks appropriate for this patch.

---
Generated by Claude Code Patch Reviewer