Re: [PATCH] tpm: Fix memory leak in tpmm_chip_alloc

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On 2022/3/7 21:45, Jarkko Sakkinen wrote:
On Mon, Mar 07, 2022 at 06:48:27PM +0800, GUO Zihua wrote:
Fix a memory leak in tpmm_chip_alloc. devm_add_action_or_reset would
call put_device on error, while tpm->devs is left untouched. Call
put_device on tpm->devs as well if devm_add_action_or_reset returns an
error.

Fixes: fdc915f7f719 ("tpm: expose spaces via a device link /dev/tpmrm")
Signed-off-by: GUO Zihua <guozihua@xxxxxxxxxx>
---
  drivers/char/tpm/tpm-chip.c | 13 +++++++++----
  1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index b009e7479b70..0a92334e8c40 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -308,6 +308,12 @@ static int tpm_class_shutdown(struct device *dev)
  	return 0;
  }
+static void tpm_chip_free(struct tpm_chip *chip)
+{
+	put_device(&chip->devs);
+	put_device(&chip->dev);
+}
+
  /**
   * tpm_chip_alloc() - allocate a new struct tpm_chip instance
   * @pdev: device to which the chip is associated
@@ -396,8 +402,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
  	return chip;
out:
-	put_device(&chip->devs);
-	put_device(&chip->dev);
+	tpm_chip_free(chip);
  	return ERR_PTR(rc);
  }
  EXPORT_SYMBOL_GPL(tpm_chip_alloc);
@@ -420,8 +425,8 @@ struct tpm_chip *tpmm_chip_alloc(struct device *pdev,
  		return chip;
rc = devm_add_action_or_reset(pdev,
-				      (void (*)(void *)) put_device,
-				      &chip->dev);
+				      (void (*)(void *)) tpm_chip_free,
+				      chip);
  	if (rc)
  		return ERR_PTR(rc);
--
2.17.1


Please test against the latest in

git://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git

and share your results.

BR, Jarkko
.

Hi Jarkko,

I'll do that. Do we have a test set for TPM? Or do we just build and run it and see if everything works as expected?

This is an error handling optimization BTW.

--
Best
GUO Zihua



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