[v3] drivers/misc: Add NULL check in aspeed_lpc_enable_snoop

Commit Message

Henry Martin March 31, 2025, 3:40 p.m. UTC

devm_kasprintf() returns NULL if memory allocation fails. Currently,
aspeed_lpc_enable_snoop() does not check for this case, leading to a NULL
pointer dereference.

The corrected code adds error checking and optimizes resource release logic
to ensure no memory or kernel resources are leaked in case of failure.

Fixes: 3772e5da4454 ("drivers/misc: Aspeed LPC snoop output using misc chardev")
Signed-off-by: Henry Martin <[e-mail]>
---
V2 -> V3: The enhanced code introduces proper error handling and
improves resource cleanup mechanisms to prevent memory or kernel
resource leaks during failure scenarios.
V1 -> V2: Removed blank line between tags.

 drivers/soc/aspeed/aspeed-lpc-snoop.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

Comments

Markus Elfring March 31, 2025, 4:15 p.m. UTC | #1

> devm_kasprintf() returns NULL if memory allocation fails. Currently,
…
                 call?                               failed?


> The corrected code adds error checking and optimizes resource release logic
…

See also once more:
https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.14#n94


An other subsystem specification might be more desirable.
https://web.git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/log/drivers/soc/aspeed/aspeed-lpc-snoop.c?h=next-20250331


* May the array access be simplified another bit here?
* How do you think about to store a pointer to a corresponding data structure member
  in an additional local variable?


Regards,
Markus

Patch

diff --git a/drivers/soc/aspeed/aspeed-lpc-snoop.c b/drivers/soc/aspeed/aspeed-lpc-snoop.c
index 9ab5ba9cf1d6..b79365a34baa 100644
--- a/drivers/soc/aspeed/aspeed-lpc-snoop.c
+++ b/drivers/soc/aspeed/aspeed-lpc-snoop.c
@@ -200,11 +200,16 @@  static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
 	lpc_snoop->chan[channel].miscdev.minor = MISC_DYNAMIC_MINOR;
 	lpc_snoop->chan[channel].miscdev.name =
 		devm_kasprintf(dev, GFP_KERNEL, "%s%d", DEVICE_NAME, channel);
+	if (!lpc_snoop->chan[channel].miscdev.name) {
+		rc = -ENOMEM;
+		goto err_free_fifo;
+	}
+
 	lpc_snoop->chan[channel].miscdev.fops = &snoop_fops;
 	lpc_snoop->chan[channel].miscdev.parent = dev;
 	rc = misc_register(&lpc_snoop->chan[channel].miscdev);
 	if (rc)
-		return rc;
+		goto err_free_fifo;
 
 	/* Enable LPC snoop channel at requested port */
 	switch (channel) {
@@ -221,7 +226,8 @@  static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
 		hicrb_en = HICRB_ENSNP1D;
 		break;
 	default:
-		return -EINVAL;
+		rc = -EINVAL;
+		goto err_misc_deregister;
 	}
 
 	regmap_update_bits(lpc_snoop->regmap, HICR5, hicr5_en, hicr5_en);
@@ -232,6 +238,12 @@  static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
 				hicrb_en, hicrb_en);
 
 	return rc;
+
+err_misc_deregister:
+	misc_deregister(&lpc_snoop->chan[channel].miscdev);
+err_free_fifo:
+	kfifo_free(&lpc_snoop->chan[channel].fifo);
+	return rc;
 }
 
 static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop,