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Subject[PATCH v4 3/3] libbpf: cleanup the legacy uprobe_event on failed add/attach_event()
Date
A potential scenario, when an error is returned after
add_uprobe_event_legacy() in perf_event_uprobe_open_legacy(), or
bpf_program__attach_perf_event_opts() in
bpf_program__attach_uprobe_opts() returns an error, the uprobe_event
that was previously created is not cleaned.

So, with this patch, when an error is returned, fix this by adding
remove_uprobe_event_legacy()

Signed-off-by: Chuang Wang <nashuiliang@gmail.com>
---
tools/lib/bpf/libbpf.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 159b69d8b941..5aa6033a0284 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -10240,9 +10240,10 @@ static int perf_event_uprobe_open_legacy(const char *probe_name, bool retprobe,
}
type = determine_uprobe_perf_type_legacy(probe_name, retprobe);
if (type < 0) {
+ err = type;
pr_warn("failed to determine legacy uprobe event id for %s:0x%zx: %d\n",
- binary_path, offset, type);
- return type;
+ binary_path, offset, err);
+ goto err_clean_legacy;
}

memset(&attr, 0, sizeof(attr));
@@ -10257,9 +10258,14 @@ static int perf_event_uprobe_open_legacy(const char *probe_name, bool retprobe,
if (pfd < 0) {
err = -errno;
pr_warn("legacy uprobe perf_event_open() failed: %d\n", err);
- return err;
+ goto err_clean_legacy;
}
return pfd;
+
+err_clean_legacy:
+ /* Clear the newly added legacy uprobe_event */
+ remove_uprobe_event_legacy(probe_name, retprobe);
+ return err;
}

/* Return next ELF section of sh_type after scn, or first of that type if scn is NULL. */
@@ -10593,7 +10599,7 @@ bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
prog->name, retprobe ? "uretprobe" : "uprobe",
binary_path, func_offset,
libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
- goto err_out;
+ goto err_clean_legacy;
}
if (legacy) {
struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
@@ -10603,10 +10609,14 @@ bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
perf_link->legacy_is_retprobe = retprobe;
}
return link;
+
+err_clean_legacy:
+ if (legacy)
+ remove_uprobe_event_legacy(legacy_probe, retprobe);
+
err_out:
free(legacy_probe);
return libbpf_err_ptr(err);
-
}

/* Format of u[ret]probe section definition supporting auto-attach:
--
2.34.1
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