FAILED: patch "[PATCH] s390/zcrypt: Guard domain index uses against speculative" failed to apply to 6.1-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 7b88e8b6d714cd1b2b6185e2963c8ec4d98542d0
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026110429-splashing-cathedral-020a@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7b88e8b6d714cd1b2b6185e2963c8ec4d98542d0 Mon Sep 17 00:00:00 2001
From: Harald Freudenberger <freude@linux.ibm.com>
Date: Tue, 6 Oct 2026 17:46:02 +0200
Subject: [PATCH] s390/zcrypt: Guard domain index uses against speculative
 bypass

The previous array_index_nospec() placement only covered the admin
permission check, leaving ap_test_config_usage_domain() and
ap_test_config_ctrl_domain() in the CCA path exposed to speculative
execution.

Move the sanitization to before all permission and config checks in
both the CCA and EP11 paths. Hold the sanitized domain value in
another variable so that the later use can choose to use either the
original value (subject to speculative execution) or the sanitized
value (which may in case of AUTOSEL_DOM reflect the wrong
value). Before that, check the domain value to be either AUTOSEL_DOM
or in range 0...AP_DOMAINS-1 and return with -EINVAL in case this check
does not pass.

Fixes: e935cd525af4 ("s390/zcrypt: Close speculative mem read possibility")
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Cc: stable@vger.kernel.org
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c
index ec6a4c2f9f04..80435fd8e6ad 100644
--- a/drivers/s390/crypto/zcrypt_api.c
+++ b/drivers/s390/crypto/zcrypt_api.c
@@ -854,7 +854,7 @@ static long _zcrypt_send_cprb(u32 xflags, struct ap_perms *perms,
 			      struct ica_xcRB *xcrb)
 {
 	bool userspace = xflags & ZCRYPT_XFLAG_USERSPACE;
-	unsigned int card, domain, func_code = 0;
+	unsigned int card, domain, _dom, func_code = 0;
 	unsigned int wgt = 0, pref_wgt = 0;
 	struct zcrypt_queue *zq, *pref_zq;
 	struct zcrypt_card *zc, *pref_zc;
@@ -877,10 +877,17 @@ static long _zcrypt_send_cprb(u32 xflags, struct ap_perms *perms,
 	print_hex_dump_debug("ccareq: ", DUMP_PREFIX_ADDRESS, 16, 1,
 			     ap_msg.msg, ap_msg.len, false);
 
+	/* Check domain for either AUTOSEL_DOM or in range 0...AP_DOMAINS-1 */
+	if (domain != AUTOSEL_DOM && domain >= AP_DOMAINS) {
+		rc = -EINVAL;
+		goto out;
+	}
+	/* Spectre-v1: sanitize domain unconditionally for later use */
+	_dom = array_index_nospec(domain, AP_DOMAINS);
+
 	if (perms != &ap_perms && domain < AP_DOMAINS) {
 		if (ap_msg.flags & AP_MSG_FLAG_ADMIN) {
-			domain = array_index_nospec(domain, AP_DOMAINS);
-			if (!test_bit_inv(domain, perms->adm)) {
+			if (!test_bit_inv(_dom, perms->adm)) {
 				rc = -ENODEV;
 				goto out;
 			}
@@ -893,10 +900,11 @@ static long _zcrypt_send_cprb(u32 xflags, struct ap_perms *perms,
 	 * If a valid target domain is set and this domain is NOT a usage
 	 * domain but a control only domain, autoselect target domain.
 	 */
-	if (domain < AP_DOMAINS &&
-	    !ap_test_config_usage_domain(domain) &&
-	    ap_test_config_ctrl_domain(domain))
-		domain = AUTOSEL_DOM;
+	if (domain < AP_DOMAINS) {
+		if (!ap_test_config_usage_domain(_dom) &&
+		    ap_test_config_ctrl_domain(_dom))
+			domain = AUTOSEL_DOM;
+	}
 
 	pref_zc = NULL;
 	pref_zq = NULL;
@@ -1041,7 +1049,7 @@ static long _zcrypt_send_ep11_cprb(u32 xflags, struct ap_perms *perms,
 	struct ep11_target_dev *targets = NULL;
 	unsigned short target_num;
 	unsigned int wgt = 0, pref_wgt = 0;
-	unsigned int func_code = 0, domain;
+	unsigned int func_code = 0, domain, _dom;
 	struct ap_message ap_msg;
 	int cpen, qpen, qid = 0, rc;
 	struct module *mod;
@@ -1078,10 +1086,17 @@ static long _zcrypt_send_ep11_cprb(u32 xflags, struct ap_perms *perms,
 	print_hex_dump_debug("ep11req: ", DUMP_PREFIX_ADDRESS, 16, 1,
 			     ap_msg.msg, ap_msg.len, false);
 
+	/* Check domain for either AUTOSEL_DOM or in range 0...AP_DOMAINS-1 */
+	if (domain != AUTOSEL_DOM && domain >= AP_DOMAINS) {
+		rc = -EINVAL;
+		goto out;
+	}
+	/* Spectre-v1: sanitize domain unconditionally for later use */
+	_dom = array_index_nospec(domain, AP_DOMAINS);
+
 	if (perms != &ap_perms && domain < AP_DOMAINS) {
 		if (ap_msg.flags & AP_MSG_FLAG_ADMIN) {
-			domain = array_index_nospec(domain, AP_DOMAINS);
-			if (!test_bit_inv(domain, perms->adm)) {
+			if (!test_bit_inv(_dom, perms->adm)) {
 				rc = -ENODEV;
 				goto out;
 			}