[PATCH bpf-next v5 1/3] bpftool: fix double close in map dump

From: Yuan Chen <[email protected]>

map_dump() closes the map fd in its error path, and do_dump() then
closes the same fd again after a successful dump. Closing an already
closed fd leaves errno set to EBADF, which poisons later errno checks
such as the batch file read check in do_batch(). Let do_dump() own the
fd and remove the close from map_dump().

The same double-close pattern exists in do_show_subset(): both
show_map_close_json() and show_map_close_plain() already close the fd,
so drop the extra close() there as well.

Also propagate the error when bpf_map_get_info_by_fd() fails on a
subsequent map in do_dump(): set err = -1 before breaking out of the
loop, so a later failure is not silently hidden after an earlier
iteration succeeded.

Fixes: 99f9863a0c45f ("bpftool: Match maps by name")
Signed-off-by: Yuan Chen <[email protected]>
---
 tools/bpf/bpftool/map.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 6b9649294ca1..684a8fb72414 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -659,8 +659,6 @@ static int do_show_subset(int argc, char **argv)
 			show_map_close_json(fds[i], &info);
 		else
 			show_map_close_plain(fds[i], &info);
-
-		close(fds[i]);
 	}
 	if (json_output && nb_fds > 1)
 		jsonw_end_array(json_wtr);	/* root array */
@@ -895,7 +893,6 @@ map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
 exit_free:
 	free(key);
 	free(value);
-	close(fd);
 	free_map_kv_btf(btf);
 
 	return err;
@@ -944,6 +941,7 @@ static int do_dump(int argc, char **argv)
 	for (i = 0; i < nb_fds; i++) {
 		if (bpf_map_get_info_by_fd(fds[i], &info, &len)) {
 			p_err("can't get map info: %s", strerror(errno));
+			err = -1;
 			break;
 		}
 		err = map_dump(fds[i], &info, wtr, nb_fds > 1);
-- 
2.54.0