[PATCH] tpm: st33zp24: check if chip is null before dereferencing

[Colin King]

From: Colin Ian King <colin.k...@canonical.com>

Currently chip is being dereferenced by the call to dev_get_drvdata
before it is being null checked, hence we have a potential null
pointer dereference bug. Fix this by only dereferencing it after the
null check.

Detected by CoverityScan, CID#1357806 ("Dereference before null check")

Fixes: 9e0d39d8a6a0 ("tpm: Remove useless priv field in struct 
tpm_vendor_specific")
Signed-off-by: Colin Ian King <colin.k...@canonical.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 f95b9c75175b..476865d66a0e 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;
@@ -378,6 +378,7 @@ static int st33zp24_send(struct tpm_chip *chip, unsigned 
char *buf,
        if (len < TPM_HEADER_SIZE)
                return -EBUSY;
 
+       tpm_dev = dev_get_drvdata(&chip->dev);
        ret = request_locality(chip);
        if (ret < 0)
                return ret;
-- 
2.15.1