linux-kernel - [PATCH v2 10/18] perf dlfilter: Be defensive against potential NULL dereference

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Message-Id: <20231005230851.3666908-11-irogers@google.com>
Date:   Thu,  5 Oct 2023 16:08:43 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>,
        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>,
        Yicong Yang <yangyicong@...ilicon.com>,
        Jonathan Cameron <jonathan.cameron@...wei.com>,
        Yang Jihong <yangjihong1@...wei.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Ming Wang <wangming01@...ngson.cn>,
        Huacai Chen <chenhuacai@...nel.org>,
        Sean Christopherson <seanjc@...gle.com>,
        K Prateek Nayak <kprateek.nayak@....com>,
        Yanteng Si <siyanteng@...ngson.cn>,
        Yuan Can <yuancan@...wei.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        James Clark <james.clark@....com>, llvm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        bpf@...r.kernel.org
Subject: [PATCH v2 10/18] perf dlfilter: Be defensive against potential NULL dereference

In the unlikely case of having a symbol without a mapping, avoid a
NULL dereference that clang-tidy warns about.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/dlfilter.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/dlfilter.c b/tools/perf/util/dlfilter.c
index 1dbf27822ee2..5e54832137a9 100644
--- a/tools/perf/util/dlfilter.c
+++ b/tools/perf/util/dlfilter.c
@@ -52,8 +52,10 @@ static void al_to_d_al(struct addr_location *al, struct perf_dlfilter_al *d_al)
 		d_al->sym_end = sym->end;
 		if (al->addr < sym->end)
 			d_al->symoff = al->addr - sym->start;
-		else
+		else if (al->map)
 			d_al->symoff = al->addr - map__start(al->map) - sym->start;
+		else
+			d_al->symoff = 0;
 		d_al->sym_binding = sym->binding;
 	} else {
 		d_al->sym = NULL;
-- 
2.42.0.609.gbb76f46606-goog