Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2021-05-04

The following pull-request contains BPF updates for your *net* tree.

We've added 5 non-merge commits during the last 4 day(s) which contain
a total of 6 files changed, 52 insertions(+), 30 deletions(-).

The main changes are:

1) Fix libbpf overflow when processing BPF ring buffer in case of extreme
   application behavior, from Brendan Jackman.

2) Fix potential data leakage of uninitialized BPF stack under speculative
   execution, from Daniel Borkmann.

3) Fix off-by-one when validating xsk pool chunks, from Xuan Zhuo.

4) Fix snprintf BPF selftest with a pid filter to avoid racing its output
   test buffer, from Florent Revest.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 28 insertions, 9 deletions

diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c
index e7a8d847161f..1d80ad4e0de8 100644
--- a/tools/lib/bpf/ringbuf.c
+++ b/tools/lib/bpf/ringbuf.c
@@ -202,9 +202,11 @@ static inline int roundup_len(__u32 len)
 	return (len + 7) / 8 * 8;
 }
 
-static int ringbuf_process_ring(struct ring* r)
+static int64_t ringbuf_process_ring(struct ring* r)
 {
-	int *len_ptr, len, err, cnt = 0;
+	int *len_ptr, len, err;
+	/* 64-bit to avoid overflow in case of extreme application behavior */
+	int64_t cnt = 0;
 	unsigned long cons_pos, prod_pos;
 	bool got_new_data;
 	void *sample;
@@ -244,12 +246,14 @@ done:
 }
 
 /* Consume available ring buffer(s) data without event polling.
- * Returns number of records consumed across all registered ring buffers, or
- * negative number if any of the callbacks return error.
+ * Returns number of records consumed across all registered ring buffers (or
+ * INT_MAX, whichever is less), or negative number if any of the callbacks
+ * return error.
  */
 int ring_buffer__consume(struct ring_buffer *rb)
 {
-	int i, err, res = 0;
+	int64_t err, res = 0;
+	int i;
 
 	for (i = 0; i < rb->ring_cnt; i++) {
 		struct ring *ring = &rb->rings[i];
@@ -259,18 +263,24 @@ int ring_buffer__consume(struct ring_buffer *rb)
 			return err;
 		res += err;
 	}
+	if (res > INT_MAX)
+		return INT_MAX;
 	return res;
 }
 
 /* Poll for available data and consume records, if any are available.
- * Returns number of records consumed, or negative number, if any of the
- * registered callbacks returned error.
+ * Returns number of records consumed (or INT_MAX, whichever is less), or
+ * negative number, if any of the registered callbacks returned error.
  */
 int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms)
 {
-	int i, cnt, err, res = 0;
+	int i, cnt;
+	int64_t err, res = 0;
 
 	cnt = epoll_wait(rb->epoll_fd, rb->events, rb->ring_cnt, timeout_ms);
+	if (cnt < 0)
+		return -errno;
+
 	for (i = 0; i < cnt; i++) {
 		__u32 ring_id = rb->events[i].data.fd;
 		struct ring *ring = &rb->rings[ring_id];
@@ -280,7 +290,9 @@ int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms)
 			return err;
 		res += err;
 	}
-	return cnt < 0 ? -errno : res;
+	if (res > INT_MAX)
+		return INT_MAX;
+	return res;
 }
 
 /* Get an fd that can be used to sleep until data is available in the ring(s) */
diff --git a/tools/testing/selftests/bpf/prog_tests/snprintf.c b/tools/testing/selftests/bpf/prog_tests/snprintf.c
index a958c22aec75..dffbcaa1ec98 100644
--- a/tools/testing/selftests/bpf/prog_tests/snprintf.c
+++ b/tools/testing/selftests/bpf/prog_tests/snprintf.c
@@ -43,6 +43,8 @@ void test_snprintf_positive(void)
 	if (!ASSERT_OK_PTR(skel, "skel_open"))
 		return;
 
+	skel->bss->pid = getpid();
+
 	if (!ASSERT_OK(test_snprintf__attach(skel), "skel_attach"))
 		goto cleanup;
 
diff --git a/tools/testing/selftests/bpf/progs/test_snprintf.c b/tools/testing/selftests/bpf/progs/test_snprintf.c
index 951a0301c553..e35129bea0a0 100644
--- a/tools/testing/selftests/bpf/progs/test_snprintf.c
+++ b/tools/testing/selftests/bpf/progs/test_snprintf.c
@@ -5,6 +5,8 @@
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 
+__u32 pid = 0;
+
 char num_out[64] = {};
 long num_ret = 0;
 
@@ -42,6 +44,9 @@ int handler(const void *ctx)
 	static const char str1[] = "str1";
 	static const char longstr[] = "longstr";
 
+	if ((int)bpf_get_current_pid_tgid() != pid)
+		return 0;
+
 	/* Integer types */
 	num_ret  = BPF_SNPRINTF(num_out, sizeof(num_out),
 				"%d %u %x %li %llu %lX",