[PATCH] char: tpm: fix potential null pointer dereference

[PATCH] char: tpm: fix potential null pointer dereference

[Gustavo A. R. Silva]

NULL check at line 376: if (!chip) {, implies chip might be NULL.
Function dev_get_drvdata() dereference pointer chip.
Move pointer tmp_dev assignment after the NULL check.

Addresses-Coverity-ID: 1397648
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
---
 drivers/char/tpm/st33zp24/st33zp24.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/st33zp24/st33zp24.c b/drivers/char/tpm/st33zp24/st33zp24.c
index 4d1dc8b..f45e8c7 100644
--- a/drivers/char/tpm/st33zp24/st33zp24.c
+++ b/drivers/char/tpm/st33zp24/st33zp24.c
@@ -367,7 +367,7 @@ static irqreturn_t tpm_ioserirq_handler(int irq, void *dev_id)
 static int st33zp24_send(struct tpm_chip *chip, unsigned char *buf,
 			 size_t len)
 {
-	struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
+	struct st33zp24_dev *tpm_dev;
 	u32 status, i, size, ordinal;
 	int burstcnt = 0;
 	int ret;
@@ -382,6 +382,7 @@ static int st33zp24_send(struct tpm_chip *chip, unsigned char *buf,
 	if (ret < 0)
 		return ret;
 
+	tpm_dev = dev_get_drvdata(&chip->dev);
 	status = st33zp24_status(chip);
 	if ((status & TPM_STS_COMMAND_READY) == 0) {
 		st33zp24_cancel(chip);
-- 
2.5.0

Re: [PATCH] char: tpm: fix potential null pointer dereference

[Jason Gunthorpe]

On Tue, May 30, 2017 at 05:05:20PM -0500, Gustavo A. R. Silva wrote:
> NULL check at line 376: if (!chip) {, implies chip might be NULL.
> Function dev_get_drvdata() dereference pointer chip.
> Move pointer tmp_dev assignment after the NULL check.

chip cannot be null in st33zp24_send, please remove the bogus if
instead.

Jason

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Re: [PATCH] char: tpm: fix potential null pointer dereference

[Gustavo A. R. Silva]

Hi Jason,

Quoting Jason Gunthorpe <jgunthorpe@obsidianresearch.com>:

> On Tue, May 30, 2017 at 05:05:20PM -0500, Gustavo A. R. Silva wrote:
>> NULL check at line 376: if (!chip) {, implies chip might be NULL.
>> Function dev_get_drvdata() dereference pointer chip.
>> Move pointer tmp_dev assignment after the NULL check.
>
> chip cannot be null in st33zp24_send, please remove the bogus if
> instead.
>

I get it.

Thanks for clarifying.
--
Gustavo A. R. Silva

[PATCH] char: tpm: remove unnecessary code

[Gustavo A. R. Silva]

Remove unnecessary code.
Pointer chip cannot be NULL in st33zp24_send().

Addresses-Coverity-ID: 1397648
Cc: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
---
 drivers/char/tpm/st33zp24/st33zp24.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/char/tpm/st33zp24/st33zp24.c b/drivers/char/tpm/st33zp24/st33zp24.c
index 4d1dc8b..ca74c24 100644
--- a/drivers/char/tpm/st33zp24/st33zp24.c
+++ b/drivers/char/tpm/st33zp24/st33zp24.c
@@ -373,8 +373,6 @@ static int st33zp24_send(struct tpm_chip *chip, unsigned char *buf,
 	int ret;
 	u8 data;
 
-	if (!chip)
-		return -EBUSY;
 	if (len < TPM_HEADER_SIZE)
 		return -EBUSY;
 
-- 
2.5.0