6.8-stable review patch. If anyone has any objections, please let me know.
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From: Quentin Monnet qmo@kernel.org
[ Upstream commit 9bf48fa19a4b1d186e08b20bf7e5de26a15644fb ]
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@kernel.org Signed-off-by: Quentin Monnet qmo@kernel.org Signed-off-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/bpf/20240314150438.232462-1-qmo@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 92bca96587a4a..5af9cab422ca3 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -7456,9 +7456,9 @@ 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) { /* @@ -7482,9 +7482,8 @@ 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;