perf bpf-event: Fix use-after-free in synthesis
Calls to perf_env__insert_bpf_prog_info may fail as a sideband thread
may already have inserted the bpf_prog_info. Such failures may yield
info_linear being freed which then causes use-after-free issues with
the internal bpf_prog_info info struct. Make it so that
perf_env__insert_bpf_prog_info trigger early non-error paths and fix
the use-after-free in perf_event__synthesize_one_bpf_prog. Add proper
return error handling to perf_env__add_bpf_info (that calls
perf_env__insert_bpf_prog_info) and propagate the return value in its
callers.
Closes: https://lore.kernel.org/lkml/CAP-5=fWJQcmUOP7MuCA2ihKnDAHUCOBLkQFEkQES-1ZZTrgf8Q@mail.gmail.com/
Fixes: 03edb7020bb9 ("perf bpf: Fix two memory leakages when calling perf_env__insert_bpf_prog_info()")
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250902181713.309797-2-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
index 5b6d3e8..2298cd3 100644
--- a/tools/perf/util/bpf-event.c
+++ b/tools/perf/util/bpf-event.c
@@ -657,9 +657,15 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_session *session,
info_node->info_linear = info_linear;
info_node->metadata = NULL;
if (!perf_env__insert_bpf_prog_info(env, info_node)) {
- free(info_linear);
+ /*
+ * Insert failed, likely because of a duplicate event
+ * made by the sideband thread. Ignore synthesizing the
+ * metadata.
+ */
free(info_node);
+ goto out;
}
+ /* info_linear is now owned by info_node and shouldn't be freed below. */
info_linear = NULL;
/*
@@ -827,18 +833,18 @@ int perf_event__synthesize_bpf_events(struct perf_session *session,
return err;
}
-static void perf_env__add_bpf_info(struct perf_env *env, u32 id)
+static int perf_env__add_bpf_info(struct perf_env *env, u32 id)
{
struct bpf_prog_info_node *info_node;
struct perf_bpil *info_linear;
struct btf *btf = NULL;
u64 arrays;
u32 btf_id;
- int fd;
+ int fd, err = 0;
fd = bpf_prog_get_fd_by_id(id);
if (fd < 0)
- return;
+ return -EINVAL;
arrays = 1UL << PERF_BPIL_JITED_KSYMS;
arrays |= 1UL << PERF_BPIL_JITED_FUNC_LENS;
@@ -852,6 +858,7 @@ static void perf_env__add_bpf_info(struct perf_env *env, u32 id)
info_linear = get_bpf_prog_info_linear(fd, arrays);
if (IS_ERR_OR_NULL(info_linear)) {
pr_debug("%s: failed to get BPF program info. aborting\n", __func__);
+ err = PTR_ERR(info_linear);
goto out;
}
@@ -862,38 +869,46 @@ static void perf_env__add_bpf_info(struct perf_env *env, u32 id)
info_node->info_linear = info_linear;
info_node->metadata = bpf_metadata_create(&info_linear->info);
if (!perf_env__insert_bpf_prog_info(env, info_node)) {
+ pr_debug("%s: duplicate add bpf info request for id %u\n",
+ __func__, btf_id);
free(info_linear);
free(info_node);
+ goto out;
}
- } else
+ } else {
free(info_linear);
+ err = -ENOMEM;
+ goto out;
+ }
if (btf_id == 0)
goto out;
btf = btf__load_from_kernel_by_id(btf_id);
- if (libbpf_get_error(btf)) {
- pr_debug("%s: failed to get BTF of id %u, aborting\n",
- __func__, btf_id);
- goto out;
+ if (!btf) {
+ err = -errno;
+ pr_debug("%s: failed to get BTF of id %u %d\n", __func__, btf_id, err);
+ } else {
+ perf_env__fetch_btf(env, btf_id, btf);
}
- perf_env__fetch_btf(env, btf_id, btf);
out:
btf__free(btf);
close(fd);
+ return err;
}
static int bpf_event__sb_cb(union perf_event *event, void *data)
{
struct perf_env *env = data;
+ int ret = 0;
if (event->header.type != PERF_RECORD_BPF_EVENT)
return -1;
switch (event->bpf.type) {
case PERF_BPF_EVENT_PROG_LOAD:
- perf_env__add_bpf_info(env, event->bpf.id);
+ ret = perf_env__add_bpf_info(env, event->bpf.id);
case PERF_BPF_EVENT_PROG_UNLOAD:
/*
@@ -907,7 +922,7 @@ static int bpf_event__sb_cb(union perf_event *event, void *data)
break;
}
- return 0;
+ return ret;
}
int evlist__add_bpf_sb_event(struct evlist *evlist, struct perf_env *env)
