tracing/histogram: Fix a potential memory leak for kstrdup()

stable inclusion
from stable-v5.10.96
commit d71b06aa995007eafd247626d0669b9364c42ad7
bugzilla: https://gitee.com/openeuler/kernel/issues/I55NWB

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d71b06aa995007eafd247626d0669b9364c42ad7

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

commit e629e7b5 upstream.

kfree() is missing on an error path to free the memory allocated by
kstrdup():

  p = param = kstrdup(data->params[i], GFP_KERNEL);

So it is better to free it via kfree(p).

Link: https://lkml.kernel.org/r/tencent_C52895FD37802832A3E5B272D05008866F0A@qq.com

Cc: stable@vger.kernel.org
Fixes: d380dcde ("tracing: Fix now invalid var_ref_vals assumption in trace action")
Signed-off-by: NXiaoke Wang <xkernel.wang@foxmail.com>
Signed-off-by: NSteven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYu Liao <liaoyu15@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

kernel/trace/trace_events_hist.c

@@ -3506,6 +3506,7 @@ static int trace_action_create(struct hist_trigger_data *hist_data,
 
 			var_ref_idx = find_var_ref_idx(hist_data, var_ref);
 			if (WARN_ON(var_ref_idx < 0)) {
+				kfree(p);
 				ret = var_ref_idx;
 				goto err;
 			}