From: Hou Tao Date: Wed, 16 Nov 2022 07:23:51 +0000 (+0800) Subject: libbpf: Check the validity of size in user_ring_buffer__reserve() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=05c1558bfcb63b95a9f530767c04c7db091560f2;p=linux.git libbpf: Check the validity of size in user_ring_buffer__reserve() 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 Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20221116072351.1168938-5-houtao@huaweicloud.com --- diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c index 5c4401cac1dbe..6af142953a940 100644 --- a/tools/lib/bpf/ringbuf.c +++ b/tools/lib/bpf/ringbuf.c @@ -486,6 +486,10 @@ 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. */