From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1FD3515C83 for ; Mon, 5 Dec 2022 19:36:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9825EC433D6; Mon, 5 Dec 2022 19:36:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1670268990; bh=hgrZDtS3QhWKMovbiQrIW4HIkXBb5Ac0lJmXD/Ko2Vs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yNjZ6er6GiOYqP1SlPWQMfRSSsMs76LDOJtaXShH7l3Yc6hRZ+Z2OwI15mM9itKos UIx237F+hZwkyJ3t7Ldmo7i1xErjRp4bzytgXnZkAqRWhGmNgnp6SJN5ZlzgkAxRt+ eV504GbGAk2cBzfVhSqPTRer1dJF/pynC/H1FtYw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Tom Zanussi , "Masami Hiramatsu (Google)" , "Steven Rostedt (Google)" Subject: [PATCH 5.15 086/120] tracing: Fix race where histograms can be called before the event Date: Mon, 5 Dec 2022 20:10:26 +0100 Message-Id: <20221205190809.172783167@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221205190806.528972574@linuxfoundation.org> References: <20221205190806.528972574@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Steven Rostedt (Google) commit ef38c79a522b660f7f71d45dad2d6244bc741841 upstream. commit 94eedf3dded5 ("tracing: Fix race where eprobes can be called before the event") fixed an issue where if an event is soft disabled, and the trigger is being added, there's a small window where the event sees that there's a trigger but does not see that it requires reading the event yet, and then calls the trigger with the record == NULL. This could be solved with adding memory barriers in the hot path, or to make sure that all the triggers requiring a record check for NULL. The latter was chosen. Commit 94eedf3dded5 set the eprobe trigger handle to check for NULL, but the same needs to be done with histograms. Link: https://lore.kernel.org/linux-trace-kernel/20221118211809.701d40c0f8a757b0df3c025a@kernel.org/ Link: https://lore.kernel.org/linux-trace-kernel/20221123164323.03450c3a@gandalf.local.home Cc: Tom Zanussi Cc: stable@vger.kernel.org Fixes: 7491e2c442781 ("tracing: Add a probe that attaches to trace events") Reported-by: Masami Hiramatsu (Google) Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_events_hist.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -4677,6 +4677,9 @@ static void event_hist_trigger(struct ev void *key = NULL; unsigned int i; + if (unlikely(!rbe)) + return; + memset(compound_key, 0, hist_data->key_size); for_each_hist_key_field(i, hist_data) {