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authorMatthew Wilcox <mawilcox@microsoft.com>2017-03-03 12:16:10 -0500
committerMatthew Wilcox <mawilcox@microsoft.com>2017-03-07 13:18:23 -0500
commit4ecd9542dbc3e07f3bd3870aac12839f72b47db4 (patch)
tree1345c7ca57563006a0355bec1bbe689dd14ca67c /tools/testing/radix-tree
parentradix tree test suite: Depend on Makefile and quieten grep (diff)
downloadlinux-dev-4ecd9542dbc3e07f3bd3870aac12839f72b47db4.tar.xz
linux-dev-4ecd9542dbc3e07f3bd3870aac12839f72b47db4.zip
ida: Free correct IDA bitmap
There's a relatively rare race where we look at the per-cpu preallocated IDA bitmap, see it's NULL, allocate a new one, and atomically update it. If the kmalloc() happened to sleep and we were rescheduled to a different CPU, or an interrupt came in at the exact right time, another task might have successfully allocated a bitmap and already deposited it. I forgot what the semantics of cmpxchg() were and ended up freeing the wrong bitmap leading to KASAN reporting a use-after-free. Dmitry found the bug with syzkaller & wrote the patch. I wrote the test case that will reproduce the bug without his patch being applied. Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Diffstat (limited to 'tools/testing/radix-tree')
-rw-r--r--tools/testing/radix-tree/idr-test.c34
-rw-r--r--tools/testing/radix-tree/main.c1
-rw-r--r--tools/testing/radix-tree/test.h1
3 files changed, 33 insertions, 3 deletions
diff --git a/tools/testing/radix-tree/idr-test.c b/tools/testing/radix-tree/idr-test.c
index 86de901fa5c6..30cd0b296f1a 100644
--- a/tools/testing/radix-tree/idr-test.c
+++ b/tools/testing/radix-tree/idr-test.c
@@ -363,7 +363,7 @@ void ida_check_random(void)
{
DEFINE_IDA(ida);
DECLARE_BITMAP(bitmap, 2048);
- int id;
+ int id, err;
unsigned int i;
time_t s = time(NULL);
@@ -377,8 +377,11 @@ void ida_check_random(void)
ida_remove(&ida, bit);
} else {
__set_bit(bit, bitmap);
- ida_pre_get(&ida, GFP_KERNEL);
- assert(!ida_get_new_above(&ida, bit, &id));
+ do {
+ ida_pre_get(&ida, GFP_KERNEL);
+ err = ida_get_new_above(&ida, bit, &id);
+ } while (err == -ENOMEM);
+ assert(!err);
assert(id == bit);
}
}
@@ -476,11 +479,36 @@ void ida_checks(void)
radix_tree_cpu_dead(1);
}
+static void *ida_random_fn(void *arg)
+{
+ rcu_register_thread();
+ ida_check_random();
+ rcu_unregister_thread();
+ return NULL;
+}
+
+void ida_thread_tests(void)
+{
+ pthread_t threads[10];
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(threads); i++)
+ if (pthread_create(&threads[i], NULL, ida_random_fn, NULL)) {
+ perror("creating ida thread");
+ exit(1);
+ }
+
+ while (i--)
+ pthread_join(threads[i], NULL);
+}
+
int __weak main(void)
{
radix_tree_init();
idr_checks();
ida_checks();
+ ida_thread_tests();
+ radix_tree_cpu_dead(1);
rcu_barrier();
if (nr_allocated)
printf("nr_allocated = %d\n", nr_allocated);
diff --git a/tools/testing/radix-tree/main.c b/tools/testing/radix-tree/main.c
index b829127d5670..bc9a78449572 100644
--- a/tools/testing/radix-tree/main.c
+++ b/tools/testing/radix-tree/main.c
@@ -368,6 +368,7 @@ int main(int argc, char **argv)
iteration_test(0, 10 + 90 * long_run);
iteration_test(7, 10 + 90 * long_run);
single_thread_tests(long_run);
+ ida_thread_tests();
/* Free any remaining preallocated nodes */
radix_tree_cpu_dead(0);
diff --git a/tools/testing/radix-tree/test.h b/tools/testing/radix-tree/test.h
index b30e11d9d271..0f8220cc6166 100644
--- a/tools/testing/radix-tree/test.h
+++ b/tools/testing/radix-tree/test.h
@@ -36,6 +36,7 @@ void iteration_test(unsigned order, unsigned duration);
void benchmark(void);
void idr_checks(void);
void ida_checks(void);
+void ida_thread_tests(void);
struct item *
item_tag_set(struct radix_tree_root *root, unsigned long index, int tag);