[PATCH bpf-next v1] bpftool: Skip prog/map that disappears while looking it up by name

[Jiayuan Chen]

Looking up a prog or map by name walks the whole id space. There is a
window between bpf_prog_get_next_id()/bpf_map_get_next_id() and getting
an fd for that id in which an unrelated object can be freed, and the
lookup then fails with ENOENT and aborts the whole command.

Skip such ids and keep walking, the same way do_show() already does.

Signed-off-by: Jiayuan Chen <jiayuan.chen@xxxxxxxxx>
---
 tools/bpf/bpftool/common.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index 8bfcff9e2f63..ef366ccc9650 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -832,6 +832,8 @@ static int prog_fd_by_nametag(void *nametag, int **fds, bool tag)
 
 		fd = bpf_prog_get_fd_by_id(id);
 		if (fd < 0) {
+			if (errno == ENOENT)
+				continue;
 			p_err("can't get prog by id (%u): %s",
 			      id, strerror(errno));
 			goto err_close_fds;
@@ -996,6 +998,8 @@ static int map_fd_by_name(char *name, int **fds,
 		opts_ro.open_flags = BPF_F_RDONLY;
 		fd = bpf_map_get_fd_by_id_opts(id, &opts_ro);
 		if (fd < 0) {
+			if (errno == ENOENT)
+				continue;
 			p_err("can't get map by id (%u): %s",
 			      id, strerror(errno));
 			goto err_close_fds;
-- 
2.43.0