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From:   Natalia Petrova <n.petrova@fintech.ru>
To:     Steven Rostedt <rostedt@goodmis.org>
CC:     Natalia Petrova <n.petrova@fintech.ru>,
        Ingo Molnar <mingo@redhat.com>, <linux-kernel@vger.kernel.org>,
        <lvc-project@linuxtesting.org>
Subject: [PATCH] trace_events_hist: add check for return value of 'create_hist_field'
Date:   Wed, 11 Jan 2023 15:04:09 +0300
Message-ID: <20230111120409.4111-1-n.petrova@fintech.ru>
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Function 'create_hist_field' is called recursively at
trace_events_hist.c:1954 and can return NULL-value that's why we have
to check it to avoid null pointer dereference.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 30350d65ac56 ("tracing: Add variable support to hist triggers")
Signed-off-by: Natalia Petrova <n.petrova@fintech.ru>
---
 kernel/trace/trace_events_hist.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index fdf784620c28..9c8c1614a78e 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1952,6 +1952,8 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 		hist_field->fn = flags & HIST_FIELD_FL_LOG2 ? hist_field_log2 :
 			hist_field_bucket;
 		hist_field->operands[0] = create_hist_field(hist_data, field, fl, NULL);
+		if (!hist_field->operands[0])
+			goto free;
 		hist_field->size = hist_field->operands[0]->size;
 		hist_field->type = kstrdup_const(hist_field->operands[0]->type, GFP_KERNEL);
 		if (!hist_field->type)
-- 
2.34.1