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Subject[PATCH] libbpf: fix crash when input null program point in USDT API
Date
The API functions bpf_program__attach_perf_event_opts and
bpf_program_attach_usdt can be invoked by users. However, when the
input prog parameter is null, the API uses name and obj without
check. This will cause program to crash directly.

Signed-off-by: Xin Liu <liuxin350@huawei.com>
---
tools/lib/bpf/libbpf.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 2a82f49ce16f..0d21de4f7d5c 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -9764,6 +9764,11 @@ struct bpf_link *bpf_program__attach_perf_event_opts(const struct bpf_program *p
if (!OPTS_VALID(opts, bpf_perf_event_opts))
return libbpf_err_ptr(-EINVAL);

+ if (!prog || !prog->name) {
+ pr_warn("prog: invalid prog\n");
+ return libbpf_err_ptr(-EINVAL);
+ }
+
if (pfd < 0) {
pr_warn("prog '%s': invalid perf event FD %d\n",
prog->name, pfd);
@@ -10967,7 +10972,7 @@ struct bpf_link *bpf_program__attach_usdt(const struct bpf_program *prog,
const struct bpf_usdt_opts *opts)
{
char resolved_path[512];
- struct bpf_object *obj = prog->obj;
+ struct bpf_object *obj;
struct bpf_link *link;
__u64 usdt_cookie;
int err;
@@ -10975,6 +10980,11 @@ struct bpf_link *bpf_program__attach_usdt(const struct bpf_program *prog,
if (!OPTS_VALID(opts, bpf_uprobe_opts))
return libbpf_err_ptr(-EINVAL);

+ if (!prog || !prog->name || !prog->obj) {
+ pr_warn("prog: invalid prog\n");
+ return libbpf_err_ptr(-EINVAL);
+ }
+
if (bpf_program__fd(prog) < 0) {
pr_warn("prog '%s': can't attach BPF program w/o FD (did you load it?)\n",
prog->name);
@@ -10997,6 +11007,7 @@ struct bpf_link *bpf_program__attach_usdt(const struct bpf_program *prog,
/* USDT manager is instantiated lazily on first USDT attach. It will
* be destroyed together with BPF object in bpf_object__close().
*/
+ obj = prog->obj;
if (IS_ERR(obj->usdt_man))
return libbpf_ptr(obj->usdt_man);
if (!obj->usdt_man) {
--
2.33.0
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