linux-kernel - [PATCH 5.10 183/545] crypto: ccp - During shutdown, check SEV data pointer before using

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Date:   Fri, 19 Aug 2022 17:39:13 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Tom Lendacky <thomas.lendacky@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 183/545] crypto: ccp - During shutdown, check SEV data pointer before using

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

[ 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@....com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 57b57d4db500..ed39a22e1b2b 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -278,7 +278,7 @@ 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);
-- 
2.35.1