[PATCH 6.18 177/396] tracing/fprobe: Roll back on enable_trace_fprobe() failure

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Raushan Patel <[email protected]>

commit aca0cd1bf16574327ef64f3178e5f5e37a61ef0b upstream.

enable_trace_fprobe() sets the file link or the TP_FLAG_PROFILE flag and
then registers each trace_fprobe in the probe list. If
__register_trace_fprobe() fails partway through, the function returns
immediately without unregistering the trace_fprobes it already registered
or undoing the file link / flag it set, leaving the event half-enabled and
leaking the registered fprobe(s).

enable_trace_kprobe() already handles this with a rollback path. Do the
same for fprobe: on failure, unregister all probes and clear the file link
or profile flag.

Link: https://lore.kernel.org/all/[email protected]/

Fixes: 334e5519c375 ("tracing/probes: Add fprobe events for tracing function entry and exit.")
Cc: [email protected]
Signed-off-by: Raushan Patel <[email protected]>
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 kernel/trace/trace_fprobe.c |   12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -1481,11 +1481,21 @@ static int enable_trace_fprobe(struct tr
 		list_for_each_entry(tf, trace_probe_probe_list(tp), tp.list) {
 			ret = __register_trace_fprobe(tf);
 			if (ret < 0)
-				return ret;
+				goto err;
 		}
 	}
 
 	return 0;
+
+err:
+	/* Failed to enable one of them. Roll back all */
+	list_for_each_entry(tf, trace_probe_probe_list(tp), tp.list)
+		__unregister_trace_fprobe(tf);
+	if (file)
+		trace_probe_remove_file(tp, file);
+	else
+		trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
+	return ret;
 }
 
 /*