[PATCH bpf-next v3 1/4] libbpf: Fix error handling in bpf_map__reuse_fd()
From: Toke Høiland-Jørgensen <hidden>
Date: 2019-10-27 20:53:48
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [library] (libbpf), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
From: Toke Høiland-Jørgensen <redacted> bpf_map__reuse_fd() was calling close() in the error path before returning an error value based on errno. However, close can change errno, so that can lead to potentially misleading error messages. Instead, explicitly store errno in the err variable before each goto. Acked-by: Andrii Nakryiko <redacted> Signed-off-by: Toke Høiland-Jørgensen <redacted> --- tools/lib/bpf/libbpf.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index d71631a01926..ce5ef3ddd263 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c@@ -1916,16 +1916,22 @@ int bpf_map__reuse_fd(struct bpf_map *map, int fd) return -errno; new_fd = open("/", O_RDONLY | O_CLOEXEC); - if (new_fd < 0) + if (new_fd < 0) { + err = -errno; goto err_free_new_name; + } new_fd = dup3(fd, new_fd, O_CLOEXEC); - if (new_fd < 0) + if (new_fd < 0) { + err = -errno; goto err_close_new_fd; + } err = zclose(map->fd); - if (err) + if (err) { + err = -errno; goto err_close_new_fd; + } free(map->name); map->fd = new_fd;
@@ -1944,7 +1950,7 @@ int bpf_map__reuse_fd(struct bpf_map *map, int fd) close(new_fd); err_free_new_name: free(new_name); - return -errno; + return err; } int bpf_map__resize(struct bpf_map *map, __u32 max_entries)