On Mar 28, 2021, at 9:10 AM, Pedro Tammela [off-list ref] wrote:

The current code only checks flags in 'bpf_ringbuf_output()'.

Signed-off-by: Pedro Tammela <redacted>
---
include/uapi/linux/bpf.h       |  8 ++++----
kernel/bpf/ringbuf.c           | 13 +++++++++++--
tools/include/uapi/linux/bpf.h |  8 ++++----
3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 100cb2e4c104..232b5e5dd045 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h

@@ -4073,7 +4073,7 @@ union bpf_attr {
 * 		Valid pointer with *size* bytes of memory available; NULL,
 * 		otherwise.
 *
- * void bpf_ringbuf_submit(void *data, u64 flags)
+ * int bpf_ringbuf_submit(void *data, u64 flags)

 * 	Description
 * 		Submit reserved ring buffer sample, pointed to by *data*.
 * 		If **BPF_RB_NO_WAKEUP** is specified in *flags*, no notification

@@ -4083,9 +4083,9 @@ union bpf_attr {
 * 		If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification
 * 		of new data availability is sent unconditionally.
 * 	Return
- * 		Nothing. Always succeeds.
+ * 		0 on success, or a negative error in case of failure.
 *
- * void bpf_ringbuf_discard(void *data, u64 flags)
+ * int bpf_ringbuf_discard(void *data, u64 flags)

 * 	Description
 * 		Discard reserved ring buffer sample, pointed to by *data*.
 * 		If **BPF_RB_NO_WAKEUP** is specified in *flags*, no notification

@@ -4095,7 +4095,7 @@ union bpf_attr {
 * 		If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification
 * 		of new data availability is sent unconditionally.
 * 	Return
- * 		Nothing. Always succeeds.
+ * 		0 on success, or a negative error in case of failure.
 *
 * u64 bpf_ringbuf_query(void *ringbuf, u64 flags)
 *	Description

diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
index f25b719ac786..f76dafe2427e 100644
--- a/kernel/bpf/ringbuf.c
+++ b/kernel/bpf/ringbuf.c

@@ -397,26 +397,35 @@ static void bpf_ringbuf_commit(void *sample, u64 flags, bool discard)

BPF_CALL_2(bpf_ringbuf_submit, void *, sample, u64, flags)
{
+	if (unlikely(flags & ~(BPF_RB_NO_WAKEUP | BPF_RB_FORCE_WAKEUP)))
+		return -EINVAL;