crypto: ccp - During shutdown, check SEV data pointer before using

BugLink: https://bugs.launchpad.net/bugs/1990162
[ Upstream commit 1b05ece0c931536c0a38a9385e243a7962e933f6 ]

On shutdown, each CCP device instance performs shutdown processing.
However, __sev_platform_shutdown_locked() uses the controlling psp
structure to obtain the pointer to the sev_device structure. However,
during driver initialization, it is possible that an error can be received
from the firmware that results in the sev_data pointer being cleared from
the controlling psp structure. The __sev_platform_shutdown_locked()
function does not check for this situation and will segfault.

While not common, this scenario should be accounted for. Add a check for a
NULL sev_device structure before attempting to use it.

Fixes: 5441a07a127f ("crypto: ccp - shutdown SEV firmware on kexec")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 8cf86dae20a473eba5b2c1a53f7e26f3378b47f5..900727b5edda554dbbf9b10b6c2b823ad0ddcdd0 100644 (file)
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -314,7 +314,7 @@ static int __sev_platform_shutdown_locked(int *error)
        struct sev_device *sev = psp_master->sev_data;
        int ret;
 
-       if (sev->state == SEV_STATE_UNINIT)
+       if (!sev || sev->state == SEV_STATE_UNINIT)
                return 0;
 
        ret = __sev_do_cmd_locked(SEV_CMD_SHUTDOWN, NULL, error);