| Message ID | 20200821191054.714731-1-yhs@fb.com |
|---|---|
| State | New |
| Headers | show |
| Series | [bpf] bpf: fix a buffer out-of-bound access when filling raw_tp link_info | expand |
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 86299a292214..ac6c784c0576 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2634,7 +2634,7 @@ 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;
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") Cc: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Yonghong Song <yhs@fb.com> --- kernel/bpf/syscall.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)