linux-hardening - [PATCH] KVM: x86/pmu: annotate struct kvm_x86_pmu_event_filter with __counted

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Message-ID: <20260212140556.3883030-2-clopez@suse.de>
Date: Thu, 12 Feb 2026 15:05:56 +0100
From: Carlos López <clopez@...e.de>
To: kvm@...r.kernel.org,
	seanjc@...gle.com,
	pbonzini@...hat.com
Cc: Carlos López <clopez@...e.de>,
	Thomas Gleixner <tglx@...nel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
	"H. Peter Anvin" <hpa@...or.com>,
	Kees Cook <kees@...nel.org>,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
	linux-hardening@...r.kernel.org (open list:KERNEL HARDENING (not covered by other areas):Keyword:\b__counted_by(_le|_be)?\b)
Subject: [PATCH] KVM: x86/pmu: annotate struct kvm_x86_pmu_event_filter with __counted_by()

struct kvm_x86_pmu_event_filter has a flexible array member, so annotate
it with the field that describes the amount of entries in such array.
Opportunistically replace the open-coded array size calculation with
flex_array_size() when copying the array portion of the struct from
userspace.

Signed-off-by: Carlos López <clopez@...e.de>
---
 arch/x86/include/asm/kvm_host.h | 2 +-
 arch/x86/kvm/pmu.c              | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index ff07c45e3c73..d9159b969bd9 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1261,7 +1261,7 @@ struct kvm_x86_pmu_event_filter {
 	__u32 nr_excludes;
 	__u64 *includes;
 	__u64 *excludes;
-	__u64 events[];
+	__u64 events[] __counted_by(nevents);
 };
 
 enum kvm_apicv_inhibit {
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index bd6b785cf261..e218352e3423 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -1256,7 +1256,7 @@ int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp)
 
 	r = -EFAULT;
 	if (copy_from_user(filter->events, user_filter->events,
-			   sizeof(filter->events[0]) * filter->nevents))
+			   flex_array_size(filter, events, filter->nevents)))
 		goto cleanup;
 
 	r = prepare_filter_lists(filter);

base-commit: e944fe2c09f405a2e2d147145c9b470084bc4c9a
-- 
2.51.0