ptp: Fix ptp_kvm_getcrosststamp issue for x86 ptp_kvm

hv_clock is preallocated to have only HVC_BOOT_ARRAY_SIZE (64) elements; if the PTP_SYS_OFFSET_PRECISE ioctl is executed on vCPUs whose index is 64 of higher, retrieving the struct pvclock_vcpu_time_info pointer with "src = &hv_clock[cpu].pvti" will result in an out-of-bounds access and a wild pointer. Change it to "this_cpu_pvti()" which is guaranteed to be valid. Fixes: 95a3d44 ("Switch kvmclock data to a PER_CPU variable") Signed-off-by: Zelin Deng <[email protected]> Cc: <[email protected]> Message-Id: <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]>
vieko · Sep 30, 2021 · 773e89a · 773e89a
1 parent ad9af93
commit 773e89a
Showing 1 changed file with 2 additions and 7 deletions.
diff --git a/drivers/ptp/ptp_kvm_x86.c b/drivers/ptp/ptp_kvm_x86.c
@@ -15,8 +15,6 @@
 #include <linux/ptp_clock_kernel.h>
 #include <linux/ptp_kvm.h>
 
-struct pvclock_vsyscall_time_info *hv_clock;
-
 static phys_addr_t clock_pair_gpa;
 static struct kvm_clock_pairing clock_pair;
 
@@ -28,8 +26,7 @@ int kvm_arch_ptp_init(void)
 		return -ENODEV;
 
 	clock_pair_gpa = slow_virt_to_phys(&clock_pair);
-	hv_clock = pvclock_get_pvti_cpu0_va();
-	if (!hv_clock)
+	if (!pvclock_get_pvti_cpu0_va())
 		return -ENODEV;
 
 	ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa,
@@ -64,10 +61,8 @@ int kvm_arch_ptp_get_crosststamp(u64 *cycle, struct timespec64 *tspec,
 	struct pvclock_vcpu_time_info *src;
 	unsigned int version;
 	long ret;
-	int cpu;
 
-	cpu = smp_processor_id();
-	src = &hv_clock[cpu].pvti;
+	src = this_cpu_pvti();
 
 	do {
 		/*