From: Hou Tao <houtao1@xxxxxxxxxx> The top two bits of size are used as busy and discard flags, so reject the reservation that has any of these special bits in the size. With the addition of validity check, these is also no need to check whether or not total_size is overflowed. Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx> --- tools/lib/bpf/ringbuf.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c index 277e49137a95..3b65f04ec46e 100644 --- a/tools/lib/bpf/ringbuf.c +++ b/tools/lib/bpf/ringbuf.c @@ -490,6 +490,10 @@ void *user_ring_buffer__reserve(struct user_ring_buffer *rb, __u32 size) __u64 cons_pos, prod_pos; struct ringbuf_hdr *hdr; + /* The top two bits are used as special flags */ + if (size & (BPF_RINGBUF_BUSY_BIT | BPF_RINGBUF_DISCARD_BIT)) + return errno = E2BIG, NULL; + /* Synchronizes with smp_store_release() in __bpf_user_ringbuf_peek() in * the kernel. */ -- 2.29.2
