1 files changed, 19 insertions, 6 deletions

diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index c6b12bed173d..335fd2ee9766 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -165,14 +165,23 @@ static struct crash_mem *fill_up_crash_elf_data(void)
 	/*
 	 * Exclusion of crash region, crashk_low_res and/or crashk_cma_ranges
 	 * may cause range splits. So add extra slots here.
+	 *
+	 * Exclusion of low 1M may not cause another range split, because the
+	 * range of exclude is [0, 1M] and the condition for splitting a new
+	 * region is that the start, end parameters are both in a certain
+	 * existing region in cmem and cannot be equal to existing region's
+	 * start or end. Obviously, the start of [0, 1M] cannot meet this
+	 * condition.
+	 *
+	 * But in order to lest the low 1M could be changed in the future,
+	 * (e.g. [start, 1M]), add a extra slot.
 	 */
-	nr_ranges += 2 + crashk_cma_cnt;
+	nr_ranges += 3 + crashk_cma_cnt;
 	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
 	if (!cmem)
 		return NULL;
 
 	cmem->max_nr_ranges = nr_ranges;
-	cmem->nr_ranges = 0;
 
 	return cmem;
 }
@@ -323,16 +332,20 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
 	struct crash_mem *cmem;
 
 	/*
-	 * Using random kexec_buf for passing dm crypt keys may cause a range
-	 * split. So use two slots here.
+	 * In the current x86 architecture code, the elfheader is always
+	 * allocated at crashk_res.start. But it depends on the allocation
+	 * position of elfheader in crashk_res. To avoid potential out of
+	 * bounds in future, add an extra slot.
+	 *
+	 * And using random kexec_buf for passing dm crypt keys may cause a
+	 * range split too, add another extra slot here.
 	 */
-	nr_ranges = 2;
+	nr_ranges = 3;
 	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
 	if (!cmem)
 		return -ENOMEM;
 
 	cmem->max_nr_ranges = nr_ranges;
-	cmem->nr_ranges = 0;
 
 	memset(&cmd, 0, sizeof(struct crash_memmap_data));
 	cmd.params = params;