[PATCH v2 2/2] kexec: Fix potential out of bounds in crash_exclude_mem_range()

[fuqiang wang]

When the split does not occur on the last array member, the current code
will not return an error. So the correct array out-of-bounds check should
be mem->nr_ranges >= mem->max_nr_ranges.

When the OOB happen, the cmem->ranges[] have changed, so return early to
avoid it.

Signed-off-by: fuqiang wang <fuqiang.wang@xxxxxxxxxxxx>
---
 kernel/crash_core.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index d4313b53837e..b1ab61c74fd2 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -611,6 +611,9 @@ int crash_exclude_mem_range(struct crash_mem *mem,
 		}
 
 		if (p_start > start && p_end < end) {
+			/* Split happened */
+			if (mem->nr_ranges >= mem->max_nr_ranges)
+				return -ENOMEM;
 			/* Split original range */
 			mem->ranges[i].end = p_start - 1;
 			temp_range.start = p_end + 1;
@@ -626,10 +629,6 @@ int crash_exclude_mem_range(struct crash_mem *mem,
 	if (!temp_range.end)
 		return 0;
 
-	/* Split happened */
-	if (i == mem->max_nr_ranges - 1)
-		return -ENOMEM;
-
 	/* Location where new range should go */
 	j = i + 1;
 	if (j < mem->nr_ranges) {
-- 
2.42.0