[PATCH] crypto: ccp: Check for NULL PSP pointer at module unload

[Tom Lendacky]

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: <sta...@vger.kernel.org> # 4.16.x-
Fixes: 2a6170dfe755 ("crypto: ccp: Add Platform Security Processor (PSP) device 
support")
Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
---
 drivers/crypto/ccp/psp-dev.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c
index 9b59638..218739b 100644
--- a/drivers/crypto/ccp/psp-dev.c
+++ b/drivers/crypto/ccp/psp-dev.c
@@ -858,6 +858,9 @@ void psp_dev_destroy(struct sp_device *sp)
 {
        struct psp_device *psp = sp->psp_data;
 
+       if (!psp)
+               return;
+
        if (psp->sev_misc)
                kref_put(&misc_dev->refcount, sev_exit);