radix-tree tests: add regression3 test

After calling radix_tree_iter_retry(), 'slot' will be set to NULL.  This
can cause radix_tree_next_slot() to dereference the NULL pointer.  Add
Konstantin Khlebnikov's test to the regression framework.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Reported-by: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 90 insertions, 1 deletions

diff --git a/tools/testing/radix-tree/Makefile b/tools/testing/radix-tree/Makefile
index e33ac3159b49..604212db9d4b 100644
--- a/tools/testing/radix-tree/Makefile
+++ b/tools/testing/radix-tree/Makefile
@@ -3,7 +3,7 @@ CFLAGS += -I. -g -Wall -D_LGPL_SOURCE
 LDFLAGS += -lpthread -lurcu
 TARGETS = main
 OFILES = main.o radix-tree.o linux.o test.o tag_check.o find_next_bit.o \
-         regression1.o regression2.o
+         regression1.o regression2.o regression3.o
 
 targets: $(TARGETS)
 
diff --git a/tools/testing/radix-tree/linux/kernel.h b/tools/testing/radix-tree/linux/kernel.h
index 27d5fe41515a..ae013b0160ac 100644
--- a/tools/testing/radix-tree/linux/kernel.h
+++ b/tools/testing/radix-tree/linux/kernel.h
@@ -13,6 +13,7 @@
 
 #define BUG_ON(expr)    assert(!(expr))
 #define __init
+#define __must_check
 #define panic(expr)
 #define printk printf
 #define __force
diff --git a/tools/testing/radix-tree/main.c b/tools/testing/radix-tree/main.c
index 6b8a412c6a11..0e83cad27a9f 100644
--- a/tools/testing/radix-tree/main.c
+++ b/tools/testing/radix-tree/main.c
@@ -261,6 +261,7 @@ int main(void)
 
         regression1_test();
         regression2_test();
+        regression3_test();
         single_thread_tests();
 
         sleep(1);
diff --git a/tools/testing/radix-tree/regression.h b/tools/testing/radix-tree/regression.h
index bb1c2ab1ae80..e018c4816688 100644
--- a/tools/testing/radix-tree/regression.h
+++ b/tools/testing/radix-tree/regression.h
@@ -3,5 +3,6 @@
 
 void regression1_test(void);
 void regression2_test(void);
+void regression3_test(void);
 
 #endif
diff --git a/tools/testing/radix-tree/regression3.c b/tools/testing/radix-tree/regression3.c
new file mode 100644
index 000000000000..17d3ba5f4a0a
--- /dev/null
+++ b/tools/testing/radix-tree/regression3.c
@@ -0,0 +1,86 @@
+/*
+ * Regression3
+ * Description:
+ * Helper radix_tree_iter_retry resets next_index to the current index.
+ * In following radix_tree_next_slot current chunk size becomes zero.
+ * This isn't checked and it tries to dereference null pointer in slot.
+ *
+ * Running:
+ * This test should run to completion immediately. The above bug would
+ * cause it to segfault.
+ *
+ * Upstream commit:
+ * Not yet
+ */
+#include <linux/kernel.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+#include <linux/radix-tree.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "regression.h"
+
+void regression3_test(void)
+{
+        RADIX_TREE(root, GFP_KERNEL);
+        void *ptr = (void *)4ul;
+        struct radix_tree_iter iter;
+        void **slot;
+        bool first;
+
+        printf("running regression test 3 (should take milliseconds)\n");
+
+        radix_tree_insert(&root, 0, ptr);
+        radix_tree_tag_set(&root, 0, 0);
+
+        first = true;
+        radix_tree_for_each_tagged(slot, &root, &iter, 0, 0) {
+//              printk("tagged %ld %p\n", iter.index, *slot);
+                if (first) {
+                        radix_tree_insert(&root, 1, ptr);
+                        radix_tree_tag_set(&root, 1, 0);
+                        first = false;
+                }
+                if (radix_tree_deref_retry(*slot)) {
+//                      printk("retry %ld\n", iter.index);
+                        slot = radix_tree_iter_retry(&iter);
+                        continue;
+                }
+        }
+        radix_tree_delete(&root, 1);
+
+        first = true;
+        radix_tree_for_each_slot(slot, &root, &iter, 0) {
+//              printk("slot %ld %p\n", iter.index, *slot);
+                if (first) {
+                        radix_tree_insert(&root, 1, ptr);
+                        first = false;
+                }
+                if (radix_tree_deref_retry(*slot)) {
+//                      printk("retry %ld\n", iter.index);
+                        slot = radix_tree_iter_retry(&iter);
+                        continue;
+                }
+        }
+        radix_tree_delete(&root, 1);
+
+        first = true;
+        radix_tree_for_each_contig(slot, &root, &iter, 0) {
+//              printk("contig %ld %p\n", iter.index, *slot);
+                if (first) {
+                        radix_tree_insert(&root, 1, ptr);
+                        first = false;
+                }
+                if (radix_tree_deref_retry(*slot)) {
+//                      printk("retry %ld\n", iter.index);
+                        slot = radix_tree_iter_retry(&iter);
+                        continue;
+                }
+        }
+
+        radix_tree_delete(&root, 0);
+        radix_tree_delete(&root, 1);
+
+        printf("regression test 3 passed\n");
+}