[SRU][F/J][PATCH 1/1] s390/pkey: Wipe copies of clear-key structures on failure

[Massimiliano Pellizzer]

From: Holger Dengler <dengler at linux.ibm.com>

[ Upstream commit d65d76a44ffe74c73298ada25b0f578680576073 ]

Wipe all sensitive data from stack for all IOCTLs, which convert a
clear-key into a protected- or secure-key.

Reviewed-by: Harald Freudenberger <freude at linux.ibm.com>
Reviewed-by: Ingo Franzki <ifranzki at linux.ibm.com>
Acked-by: Heiko Carstens <hca at linux.ibm.com>
Signed-off-by: Holger Dengler <dengler at linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev at linux.ibm.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
(backported from commit 7f6243edd901b75aaece326c90a1cc0dcb60cc3d linux-6.9.y)
[mpellizzer: backported solving merge conflicts due to surrounding
instructions which do not affect the patch]
CVE-2024-42156
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.com>
---
 drivers/s390/crypto/pkey_api.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/s390/crypto/pkey_api.c b/drivers/s390/crypto/pkey_api.c
index 43dd937cdfba1..1459b7da3af48 100644
--- a/drivers/s390/crypto/pkey_api.c
+++ b/drivers/s390/crypto/pkey_api.c
@@ -1167,9 +1167,7 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 		rc = cca_clr2seckey(kcs.cardnr, kcs.domain, kcs.keytype,
 				    kcs.clrkey.clrkey, kcs.seckey.seckey);
 		DEBUG_DBG("%s cca_clr2seckey()=%d\n", __func__, rc);
-		if (rc)
-			break;
-		if (copy_to_user(ucs, &kcs, sizeof(kcs)))
+		if (!rc && copy_to_user(ucs, &kcs, sizeof(kcs)))
 			rc = -EFAULT;
 		memzero_explicit(&kcs, sizeof(kcs));
 		break;
@@ -1199,9 +1197,7 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 		rc = pkey_clr2protkey(kcp.keytype,
 				      &kcp.clrkey, &kcp.protkey);
 		DEBUG_DBG("%s pkey_clr2protkey()=%d\n", __func__, rc);
-		if (rc)
-			break;
-		if (copy_to_user(ucp, &kcp, sizeof(kcp)))
+		if (!rc && copy_to_user(ucp, &kcp, sizeof(kcp)))
 			rc = -EFAULT;
 		memzero_explicit(&kcp, sizeof(kcp));
 		break;
@@ -1346,11 +1342,14 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 		if (copy_from_user(&kcs, ucs, sizeof(kcs)))
 			return -EFAULT;
 		apqns = _copy_apqns_from_user(kcs.apqns, kcs.apqn_entries);
-		if (IS_ERR(apqns))
+		if (IS_ERR(apqns)) {
+			memzero_explicit(&kcs, sizeof(kcs));
 			return PTR_ERR(apqns);
+		}
 		kkey = kmalloc(klen, GFP_KERNEL);
 		if (!kkey) {
 			kfree(apqns);
+			memzero_explicit(&kcs, sizeof(kcs));
 			return -ENOMEM;
 		}
 		rc = pkey_clr2seckey2(apqns, kcs.apqn_entries,
@@ -1360,15 +1359,18 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 		kfree(apqns);
 		if (rc) {
 			kfree(kkey);
+			memzero_explicit(&kcs, sizeof(kcs));
 			break;
 		}
 		if (kcs.key) {
 			if (kcs.keylen < klen) {
 				kfree(kkey);
+				memzero_explicit(&kcs, sizeof(kcs));
 				return -EINVAL;
 			}
 			if (copy_to_user(kcs.key, kkey, klen)) {
 				kfree(kkey);
+				memzero_explicit(&kcs, sizeof(kcs));
 				return -EFAULT;
 			}
 		}
-- 
2.43.0