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authorMartin KaFai Lau <martin.lau@kernel.org>2024-02-16 00:12:18 +0300
committerDaniel Borkmann <daniel@iogearbox.net>2024-02-19 14:26:46 +0300
commit3f00e4a9c96f4488a924aff4e35b77c8eced897e (patch)
treef715138a7e72079c5e8608da6113196f1ac19f5d /tools
parent0281b919e175bb9c3128bd3872ac2903e9436e3f (diff)
downloadlinux-3f00e4a9c96f4488a924aff4e35b77c8eced897e.tar.xz
selftests/bpf: Test racing between bpf_timer_cancel_and_free and bpf_timer_cancel
This selftest is based on a Alexei's test adopted from an internal user to troubleshoot another bug. During this exercise, a separate racing bug was discovered between bpf_timer_cancel_and_free and bpf_timer_cancel. The details can be found in the previous patch. This patch is to add a selftest that can trigger the bug. I can trigger the UAF everytime in my qemu setup with KASAN. The idea is to have multiple user space threads running in a tight loop to exercise both bpf_map_update_elem (which calls into bpf_timer_cancel_and_free) and bpf_timer_cancel. Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/bpf/20240215211218.990808-2-martin.lau@linux.dev
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/bpf/prog_tests/timer.c35
-rw-r--r--tools/testing/selftests/bpf/progs/timer.c34
2 files changed, 67 insertions, 2 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/timer.c b/tools/testing/selftests/bpf/prog_tests/timer.c
index 760ad96b4be0..d66687f1ee6a 100644
--- a/tools/testing/selftests/bpf/prog_tests/timer.c
+++ b/tools/testing/selftests/bpf/prog_tests/timer.c
@@ -4,10 +4,29 @@
#include "timer.skel.h"
#include "timer_failure.skel.h"
+#define NUM_THR 8
+
+static void *spin_lock_thread(void *arg)
+{
+ int i, err, prog_fd = *(int *)arg;
+ LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+ for (i = 0; i < 10000; i++) {
+ err = bpf_prog_test_run_opts(prog_fd, &topts);
+ if (!ASSERT_OK(err, "test_run_opts err") ||
+ !ASSERT_OK(topts.retval, "test_run_opts retval"))
+ break;
+ }
+
+ pthread_exit(arg);
+}
+
static int timer(struct timer *timer_skel)
{
- int err, prog_fd;
+ int i, err, prog_fd;
LIBBPF_OPTS(bpf_test_run_opts, topts);
+ pthread_t thread_id[NUM_THR];
+ void *ret;
err = timer__attach(timer_skel);
if (!ASSERT_OK(err, "timer_attach"))
@@ -43,6 +62,20 @@ static int timer(struct timer *timer_skel)
/* check that code paths completed */
ASSERT_EQ(timer_skel->bss->ok, 1 | 2 | 4, "ok");
+ prog_fd = bpf_program__fd(timer_skel->progs.race);
+ for (i = 0; i < NUM_THR; i++) {
+ err = pthread_create(&thread_id[i], NULL,
+ &spin_lock_thread, &prog_fd);
+ if (!ASSERT_OK(err, "pthread_create"))
+ break;
+ }
+
+ while (i) {
+ err = pthread_join(thread_id[--i], &ret);
+ if (ASSERT_OK(err, "pthread_join"))
+ ASSERT_EQ(ret, (void *)&prog_fd, "pthread_join");
+ }
+
return 0;
}
diff --git a/tools/testing/selftests/bpf/progs/timer.c b/tools/testing/selftests/bpf/progs/timer.c
index 8b946c8188c6..f615da97df26 100644
--- a/tools/testing/selftests/bpf/progs/timer.c
+++ b/tools/testing/selftests/bpf/progs/timer.c
@@ -51,7 +51,8 @@ struct {
__uint(max_entries, 1);
__type(key, int);
__type(value, struct elem);
-} abs_timer SEC(".maps"), soft_timer_pinned SEC(".maps"), abs_timer_pinned SEC(".maps");
+} abs_timer SEC(".maps"), soft_timer_pinned SEC(".maps"), abs_timer_pinned SEC(".maps"),
+ race_array SEC(".maps");
__u64 bss_data;
__u64 abs_data;
@@ -390,3 +391,34 @@ int BPF_PROG2(test5, int, a)
return 0;
}
+
+static int race_timer_callback(void *race_array, int *race_key, struct bpf_timer *timer)
+{
+ bpf_timer_start(timer, 1000000, 0);
+ return 0;
+}
+
+SEC("syscall")
+int race(void *ctx)
+{
+ struct bpf_timer *timer;
+ int err, race_key = 0;
+ struct elem init;
+
+ __builtin_memset(&init, 0, sizeof(struct elem));
+ bpf_map_update_elem(&race_array, &race_key, &init, BPF_ANY);
+
+ timer = bpf_map_lookup_elem(&race_array, &race_key);
+ if (!timer)
+ return 1;
+
+ err = bpf_timer_init(timer, &race_array, CLOCK_MONOTONIC);
+ if (err && err != -EBUSY)
+ return 1;
+
+ bpf_timer_set_callback(timer, race_timer_callback);
+ bpf_timer_start(timer, 0, 0);
+ bpf_timer_cancel(timer);
+
+ return 0;
+}