From: Quentin Monnet <qmo@xxxxxxxxxx>
In bpf_objec_load_prog(), there's no guarantee that obj->btf is non-NULL
when passing it to btf__fd(), and this function does not perform any
check before dereferencing its argument (as bpf_object__btf_fd() used to
do). As a consequence, we get segmentation fault errors in bpftool (for
example) when trying to load programs that come without BTF information.
v2: Keep btf__fd() in the fix instead of reverting to bpf_object__btf_fd().
Fixes: df7c3f7d3a3d ("libbpf: make uniform use of btf__fd() accessor inside libbpf")
Suggested-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Signed-off-by: Quentin Monnet <qmo@xxxxxxxxxx>
---
v1 was: 'Revert "libbpf: make uniform use of btf__fd() accessor inside libbpf"'
---
tools/lib/bpf/libbpf.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index efab29b8935b..124883eaa0cf 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -7317,9 +7317,9 @@ static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog
char *cp, errmsg[STRERR_BUFSIZE];
size_t log_buf_size = 0;
char *log_buf = NULL, *tmp;
- int btf_fd, ret, err;
bool own_log_buf = true;
__u32 log_level = prog->log_level;
+ int ret, err;
if (prog->type == BPF_PROG_TYPE_UNSPEC) {
/*
@@ -7343,9 +7343,8 @@ static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog
load_attr.prog_ifindex = prog->prog_ifindex;
/* specify func_info/line_info only if kernel supports them */
- btf_fd = btf__fd(obj->btf);
- if (btf_fd >= 0 && kernel_supports(obj, FEAT_BTF_FUNC)) {
- load_attr.prog_btf_fd = btf_fd;
+ if (obj->btf && btf__fd(obj->btf) >= 0 && kernel_supports(obj, FEAT_BTF_FUNC)) {
+ load_attr.prog_btf_fd = btf__fd(obj->btf);
load_attr.func_info = prog->func_info;
load_attr.func_info_rec_size = prog->func_info_rec_size;
load_attr.func_info_cnt = prog->func_info_cnt;
--
2.34.1
