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From:   trix@redhat.com
To:     rostedt@goodmis.org, mingo@redhat.com, natechancellor@gmail.com,
        ndesaulniers@google.com, tom.zanussi@linux.intel.com,
        baohong.liu@intel.com
Cc:     linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
        Tom Rix <trix@redhat.com>
Subject: [PATCH] tracing: fix double free
Date:   Mon,  7 Sep 2020 06:58:45 -0700
Message-Id: <20200907135845.15804-1-trix@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Tom Rix <trix@redhat.com>

clang static analyzer reports this problem

trace_events_hist.c:3824:3: warning: Attempt to free
  released memory
    kfree(hist_data->attrs->var_defs.name[i]);

In parse_var_defs() if there is a problem allocating
var_defs.expr, the earlier var_defs.name is freed.
This free is duplicated by free_var_defs() which frees
the rest of the list.

Because free_var_defs() has to run anyway, remove the
second free fom parse_var_defs().

Fixes: 30350d65ac56 ("tracing: Add variable support to hist triggers")
Signed-off-by: Tom Rix <trix@redhat.com>
---
 kernel/trace/trace_events_hist.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 0b933546142e..1b2ef6490229 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -3865,7 +3865,6 @@ static int parse_var_defs(struct hist_trigger_data *hist_data)
 
 			s = kstrdup(field_str, GFP_KERNEL);
 			if (!s) {
-				kfree(hist_data->attrs->var_defs.name[n_vars]);
 				ret = -ENOMEM;
 				goto free;
 			}
-- 
2.18.1