lib: interval_tree_test: validate benchmark parameters

The interval tree runtime test accepts module parameters that are later
used as divisors while generating randomized intervals and while reporting
average timings.  For example, max_endpoint=1 makes the generated interval
end value zero and the next modulo operation divides by that zero value.

Reject non-positive counts and require max_endpoint to provide at least
one non-zero generated endpoint before the test allocates state or starts
the benchmark.

[akpm@linux-foundation.org: include printk.h for pr_warn()]
Assisted-by: Codex:gpt-5.5-cyber-preview
Signed-off-by: Samuel Moelius <sam.moelius@trailofbits.com>
Link: https://lore.kernel.org/20260609005446.1241288.1525a5964698.interval-tree-test-small-max-endpoint-div0@trailofbits.com
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/lib/interval_tree_test.c b/lib/interval_tree_test.c
index 16200feacbf32e0fe7c15186a8415bd52ebccc6d..eba2d3e28980098a29353a4a5537288526b40d12 100644 (file)
--- a/lib/interval_tree_test.c
+++ b/lib/interval_tree_test.c
@@ -4,6 +4,7 @@
 #include <linux/interval_tree.h>
 #include <linux/prandom.h>
 #include <linux/slab.h>
+#include <linux/printk.h>
 #include <asm/timex.h>
 #include <linux/bitmap.h>
 #include <linux/maple_tree.h>
@@ -311,6 +312,27 @@ static inline int span_iteration_check(void) {return 0; }
 
 static int interval_tree_test_init(void)
 {
+       if (nnodes <= 0) {
+               pr_warn("nnodes must be positive\n");
+               return -EINVAL;
+       }
+       if (nsearches <= 0) {
+               pr_warn("nsearches must be positive\n");
+               return -EINVAL;
+       }
+       if (perf_loops <= 0) {
+               pr_warn("perf_loops must be positive\n");
+               return -EINVAL;
+       }
+       if (search_loops <= 0) {
+               pr_warn("search_loops must be positive\n");
+               return -EINVAL;
+       }
+       if (max_endpoint < 2) {
+               pr_warn("max_endpoint must be at least 2\n");
+               return -EINVAL;
+       }
+
        nodes = kmalloc_objs(struct interval_tree_node, nnodes);
        if (!nodes)
                return -ENOMEM;