[Patch v4 1/5] perf/x86: Disable LBR if x86_pmu.lbr_nr exceeds MAX_LBR_ENTRIES

[Dapeng Mi]

Disable LBR if x86_pmu.lbr_nr is larger than MAX_LBR_ENTRIES, preventing
out-of-bounds access in the cached LBR stack handling path.

Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
---
 arch/x86/events/core.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 4df792b139e0..002a04c149c2 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2645,6 +2645,12 @@ static int __init init_hw_perf_events(void)
 	if (!x86_pmu.config_mask)
 		x86_pmu.config_mask = X86_RAW_EVENT_MASK;
 
+	if (x86_pmu.lbr_nr > MAX_LBR_ENTRIES) {
+		pr_warn("LBR entries %d exceeds max %d, disable LBR.\n",
+			x86_pmu.lbr_nr, MAX_LBR_ENTRIES);
+		x86_pmu.lbr_nr = 0;
+	}
+
 	perf_events_lapic_init();
 	register_nmi_handler(NMI_LOCAL, perf_event_nmi_handler, 0, "PMI");
 
-- 
2.34.1