linux-kernel - [PATCH v1 18/20] perf machine: Fix leak of kernel dso

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Date:   Tue,  6 Jun 2023 18:43:51 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     John Garry <john.g.garry@...cle.com>,
        Will Deacon <will@...nel.org>,
        James Clark <james.clark@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        German Gomez <german.gomez@....com>,
        Ali Saidi <alisaidi@...zon.com>,
        Jing Zhang <renyu.zj@...ux.alibaba.com>,
        "Martin Liška" <mliska@...e.cz>,
        Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
        Miguel Ojeda <ojeda@...nel.org>,
        ye xingchen <ye.xingchen@....com.cn>,
        Liam Howlett <liam.howlett@...cle.com>,
        Dmitrii Dolgov <9erthalion6@...il.com>,
        "Shawn M. Chapla" <schapla@...eweavers.com>,
        Yang Jihong <yangjihong1@...wei.com>,
        K Prateek Nayak <kprateek.nayak@....com>,
        Changbin Du <changbin.du@...wei.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Sean Christopherson <seanjc@...gle.com>,
        Raul Silvera <rsilvera@...gle.com>,
        Andi Kleen <ak@...ux.intel.com>,
        "Steinar H. Gunderson" <sesse@...gle.com>,
        Yuan Can <yuancan@...wei.com>,
        Brian Robbins <brianrob@...ux.microsoft.com>,
        liuwenyu <liuwenyu7@...wei.com>,
        Ivan Babrou <ivan@...udflare.com>,
        Fangrui Song <maskray@...gle.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, coresight@...ts.linaro.org
Subject: [PATCH v1 18/20] perf machine: Fix leak of kernel dso

The kernel dso may be found by searching dsos or allocating if not
found. The allocation returns with a reference count of 2, once for
the dsos list and once for the returned value. The list search has a
reference count of 1, once for the dsos list. To make the reference
counts consistent, increase the dsos list search reference count to 2
with a dso__get, and do a put when the scope ends for either the
allocated or found dso.

This issue was found with leak sanitizer and reference count checking.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/machine.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 46af5e9748c9..f8e6c07f0048 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1868,7 +1868,7 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
 				continue;
 
 
-			kernel = dso;
+			kernel = dso__get(dso);
 			break;
 		}
 
@@ -1913,6 +1913,7 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
 			 */
 			dso__load(kernel, machine__kernel_map(machine));
 		}
+		dso__put(kernel);
 	} else if (perf_event__is_extra_kernel_mmap(machine, xm)) {
 		return machine__process_extra_kernel_map(machine, xm);
 	}
-- 
2.41.0.rc0.172.g3f132b7071-goog