iommu/intel: Fix out-of-bounds memset in dmar_latency_disable()

[ Upstream commit 754f8ef ]

dmar_latency_disable() intends to zero out only the single
latency_statistic entry for the given type, but the memset size was
computed as sizeof(*lstat) * DMAR_LATENCY_NUM, which clears the entire
array starting from &lstat[type].

When type > 0, this writes beyond the end of the allocated array,
corrupting adjacent memory.

Fix by using sizeof(*lstat) to clear only the target entry.

Fixes: 55ee5e6 ("iommu/vt-d: Add common code for dmar latency performance monitors")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: lrq-max

drivers/iommu/intel/perf.c

@@ -63,7 +63,7 @@ void dmar_latency_disable(struct intel_iommu *iommu, enum latency_type type)
 		return;
 
 	spin_lock_irqsave(&latency_lock, flags);
-	memset(&lstat[type], 0, sizeof(*lstat) * DMAR_LATENCY_NUM);
+	memset(&lstat[type], 0, sizeof(*lstat));
 	spin_unlock_irqrestore(&latency_lock, flags);
 }