linux-kernel - [PATCH] s390/kvm: Replace sprintf with snprintf for buffer safety

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Message-ID: <20251001174046.192295-1-hi@josie.lol>
Date: Wed,  1 Oct 2025 19:40:46 +0200
From: Josephine Pfeiffer <hi@...ie.lol>
To: Christian Borntraeger <borntraeger@...ux.ibm.com>
Cc: Janosch Frank <frankja@...ux.ibm.com>,
	Claudio Imbrenda <imbrenda@...ux.ibm.com>,
	David Hildenbrand <david@...hat.com>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Sven Schnelle <svens@...ux.ibm.com>,
	kvm@...r.kernel.org,
	linux-s390@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] s390/kvm: Replace sprintf with snprintf for buffer safety

Replace sprintf() with snprintf() when formatting debug names to prevent
potential buffer overflow. The debug_name buffer is 16 bytes, and while
unlikely to overflow with current PIDs, using snprintf() provides proper
bounds checking.

Signed-off-by: Josephine Pfeiffer <hi@...ie.lol>
---
 arch/s390/kvm/kvm-s390.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 6d51aa5f66be..005c117be086 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -3371,7 +3371,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 			((char *) kvm->arch.sca + sca_offset);
 	mutex_unlock(&kvm_lock);
 
-	sprintf(debug_name, "kvm-%u", current->pid);
+	snprintf(debug_name, sizeof(debug_name), "kvm-%u", current->pid);
 
 	kvm->arch.dbf = debug_register(debug_name, 32, 1, 7 * sizeof(long));
 	if (!kvm->arch.dbf)
-- 
2.51.0