From: Yonghong Song yhs@fb.com
[ Upstream commit b474959d5afda6e341a02c85f9595d85d39189ae ]
Commit f2e10bff16a0 ("bpf: Add support for BPF_OBJ_GET_INFO_BY_FD for bpf_link") added link query for raw_tp. One of fields in link_info is to fill a user buffer with tp_name. The Scurrent checking only declares "ulen && !ubuf" as invalid. So "!ulen && ubuf" will be valid. Later on, we do "copy_to_user(ubuf, tp_name, ulen - 1)" which may overwrite user memory incorrectly.
This patch fixed the problem by disallowing "!ulen && ubuf" case as well.
Fixes: f2e10bff16a0 ("bpf: Add support for BPF_OBJ_GET_INFO_BY_FD for bpf_link") Signed-off-by: Yonghong Song yhs@fb.com Signed-off-by: Alexei Starovoitov ast@kernel.org Acked-by: Andrii Nakryiko andriin@fb.com Link: https://lore.kernel.org/bpf/20200821191054.714731-1-yhs@fb.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/syscall.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 0fd80ac81f705..72e943b3bd656 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2629,7 +2629,7 @@ static int bpf_raw_tp_link_fill_link_info(const struct bpf_link *link, u32 ulen = info->raw_tracepoint.tp_name_len; size_t tp_len = strlen(tp_name);
- if (ulen && !ubuf) + if (!ulen ^ !ubuf) return -EINVAL;
info->raw_tracepoint.tp_name_len = tp_len + 1;