[PATCH 4.18 11/22] crypto: ccp - Check for NULL PSP pointer at module unload

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tom Lendacky <thomas.lendacky@amd.com>

commit afb31cd2d1a1bc3ca055fb2519ec4e9ab969ffe0 upstream.

Should the PSP initialization fail, the PSP data structure will be
freed and the value contained in the sp_device struct set to NULL.
At module unload, psp_dev_destroy() does not check if the pointer
value is NULL and will end up dereferencing a NULL pointer.

Add a pointer check of the psp_data field in the sp_device struct
in psp_dev_destroy() and return immediately if it is NULL.

Cc: <redacted> # 4.16.x-
Fixes: 2a6170dfe755 ("crypto: ccp: Add Platform Security Processor (PSP) device support")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Gary R Hook <redacted>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/crypto/ccp/psp-dev.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/crypto/ccp/psp-dev.c
+++ b/drivers/crypto/ccp/psp-dev.c

@@ -856,6 +856,9 @@ void psp_dev_destroy(struct sp_device *s
 {
 	struct psp_device *psp = sp->psp_data;
 
+	if (!psp)
+		return;
+
 	if (psp->sev_misc)
 		kref_put(&misc_dev->refcount, sev_exit);