[PATCH v15 10/23] crash_core: Introduce CRASH_HOTPLUG_SAFETY_PADDING for memory hotplug safety

[Jinjie Ruan]

Introduce CRASH_HOTPLUG_SAFETY_PADDING to allocate extra slots
for the crash memory ranges array, mitigating potential TOCTOU races
caused by concurrent memory hotplug events. When CONFIG_MEMORY_HOTPLUG
is disabled, the padding safely defaults to 0 as the memory
layout remains static.

Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
---
 include/linux/crash_core.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index c1dee3f971a9..d4762e000098 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -14,6 +14,12 @@ struct crash_mem {
 	struct range ranges[] __counted_by(max_nr_ranges);
 };
 
+#ifdef CONFIG_MEMORY_HOTPLUG
+#define CRASH_HOTPLUG_SAFETY_PADDING 128
+#else
+#define CRASH_HOTPLUG_SAFETY_PADDING 0
+#endif
+
 #ifdef CONFIG_CRASH_DUMP
 
 int crash_shrink_memory(unsigned long new_size);
-- 
2.34.1