[PATCH 2/5] tpm: tpm_nsc: fix NULL pointer dereference on init failure

[Pei Xiao]

tpm_nsc_remove() is used as the release callback of the hand-created
platform device and dereferences the chip drvdata unconditionally.
If init fails before tpmm_chip_alloc() (e.g. request_region() cannot
claim the ports), the error path drops the last device reference and
the release callback runs with chip == NULL, crashing module init.

Return early when the chip has not been created yet.

Fixes: afb5abc262e9 ("tpm: two-phase chip management functions")
Assisted-by: GLM-5.3
Signed-off-by: Pei Xiao <xiaopei01@xxxxxxxxxx>
---
 drivers/char/tpm/tpm_nsc.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm_nsc.c b/drivers/char/tpm/tpm_nsc.c
index 879ac88f5783..46a52dc99b14 100644
--- a/drivers/char/tpm/tpm_nsc.c
+++ b/drivers/char/tpm/tpm_nsc.c
@@ -259,7 +259,12 @@ static struct platform_device *pdev = NULL;
 static void tpm_nsc_remove(struct device *dev)
 {
 	struct tpm_chip *chip = dev_get_drvdata(dev);
-	struct tpm_nsc_priv *priv = dev_get_drvdata(&chip->dev);
+	struct tpm_nsc_priv *priv;
+
+	if (!chip)
+		return;
+
+	priv = dev_get_drvdata(&chip->dev);
 
 	tpm_chip_unregister(chip);
 	release_region(priv->base, 2);
-- 
2.25.1