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

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

[Tom Lendacky]

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>
---
 drivers/crypto/ccp/sev-dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 799b476fc3e8..7baf7659c7c5 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -503,7 +503,7 @@ 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);
-- 
2.36.1

Re: [PATCH] crypto: ccp - During shutdown, check SEV data pointer before using

[Herbert Xu]

On Thu, Jun 16, 2022 at 10:26:18AM -0500, Tom Lendacky wrote:
> 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>
> ---
>  drivers/crypto/ccp/sev-dev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt