[PATCH] tracing: Fix some alloc_event_probe() error handling bugs

Dan Carpenter
2021-08-24T11:52:29Z

There are two bugs in this code. First, if the kzalloc() fails it leads
to a NULL dereference of "ep" on the next line. Second, if the
alloc_event_probe() function retursn an error then it leads to an
error pointer dereference in the caller.

Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
kernel/trace/trace_eprobe.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
index 56a96e9750cf..3044b762cbd7 100644
--- a/kernel/trace/trace_eprobe.c
+++ b/kernel/trace/trace_eprobe.c
@@ -151,7 +151,7 @@ static struct trace_eprobe *alloc_event_probe(const char *group,

ep = kzalloc(struct_size(ep, tp.args, nargs), GFP_KERNEL);
if (!ep) {
- trace_event_put_ref(ep->event);
+ trace_event_put_ref(event);
goto error;
}
ep->event = event;
@@ -851,7 +851,8 @@ static int __trace_eprobe_create(int argc, const char *argv[])
ret = PTR_ERR(ep);
/* This must return -ENOMEM, else there is a bug */
WARN_ON_ONCE(ret != -ENOMEM);
- goto error; /* We know ep is not allocated */
+ ep = NULL;
+ goto error;
}

argc -= 2; argv += 2;
--
2.20.1