Subject: FAILED: patch "[PATCH] s390/perf_cpum_cf: Add missing array_index_nospec() to" failed to apply to 5.10-stable tree
To: sumanthk@linux.ibm.com,gor@linux.ibm.com,iii@linux.ibm.com,tmricht@linux.ibm.com
Cc: <stable@vger.kernel.org>
From: <gregkh@linuxfoundation.org>
Date: Mon, 20 Jul 2026 14:39:26 +0200
Message-ID: <2026072026-maturing-tapeless-9870@gregkh>
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The patch below does not apply to the 5.10-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-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 49145bce539117db4b6e9e83c0e5ef528e361050
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026072026-maturing-tapeless-9870@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Possible dependencies:


thanks,

greg k-h

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

From 49145bce539117db4b6e9e83c0e5ef528e361050 Mon Sep 17 00:00:00 2001
From: Sumanth Korikkar <sumanthk@linux.ibm.com>
Date: Mon, 6 Jul 2026 12:46:31 +0200
Subject: [PATCH] s390/perf_cpum_cf: Add missing array_index_nospec() to
 __hw_perf_event_init()

ev variable is userspace controlled via event->attr.config and used
as an array index after bounds checking, but without speculation
barriers.

Add the missing array_index_nospec() call to prevent speculative
execution.

Cc: stable@vger.kernel.org
Fixes: 212188a596d1 ("[S390] perf: add support for s390x CPU counters")
Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c
index 7aa655664ecc..2076ac22e2c4 100644
--- a/arch/s390/kernel/perf_cpum_cf.c
+++ b/arch/s390/kernel/perf_cpum_cf.c
@@ -15,6 +15,7 @@
 #include <linux/init.h>
 #include <linux/miscdevice.h>
 #include <linux/perf_event.h>
+#include <linux/nospec.h>
 
 #include <asm/cpu_mf.h>
 #include <asm/hwctrset.h>
@@ -768,6 +769,7 @@ static int __hw_perf_event_init(struct perf_event *event, unsigned int type)
 			if (!is_userspace_event(ev)) {
 				if (ev >= ARRAY_SIZE(cpumf_generic_events_user))
 					return -EOPNOTSUPP;
+				ev = array_index_nospec(ev, ARRAY_SIZE(cpumf_generic_events_user));
 				ev = cpumf_generic_events_user[ev];
 			}
 		} else if (!attr->exclude_kernel && attr->exclude_user) {
@@ -778,6 +780,7 @@ static int __hw_perf_event_init(struct perf_event *event, unsigned int type)
 			if (!is_userspace_event(ev)) {
 				if (ev >= ARRAY_SIZE(cpumf_generic_events_basic))
 					return -EOPNOTSUPP;
+				ev = array_index_nospec(ev, ARRAY_SIZE(cpumf_generic_events_basic));
 				ev = cpumf_generic_events_basic[ev];
 			}
 		}