[PATCH AUTOSEL 5.1 102/141] perf annotate: Fix dereferencing freed memory found by the smatch tool

Sasha Levin
2019-07-19T04:29:01Z

From: Leo Yan <leo.yan@linaro.org>

[ Upstream commit 600c787dbf6521d8d07ee717ab7606d5070103ea ]

Based on the following report from Smatch, fix the potential
dereferencing freed memory check.

tools/perf/util/annotate.c:1125
disasm_line__parse() error: dereferencing freed memory 'namep'

tools/perf/util/annotate.c
1100 static int disasm_line__parse(char *line, const char **namep, char **rawp)
1101 {
1102 char tmp, *name = ltrim(line);

[...]

1114 *namep = strdup(name);
1115
1116 if (*namep == NULL)
1117 goto out_free_name;

[...]

1124 out_free_name:
1125 free((void *)namep);
^^^^^
1126 *namep = NULL;
^^^^^^
1127 return -1;
1128 }

If strdup() fails to allocate memory space for *namep, we don't need to
free memory with pointer 'namep', which is resident in data structure
disasm_line::ins::name; and *namep is NULL pointer for this failure, so
it's pointless to assign NULL to *namep again.

Committer note:

Freeing namep, which is the address of the first entry of the 'struct
ins' that is the first member of struct disasm_line would in fact free
that disasm_line instance, if it was allocated via malloc/calloc, which,
later, would a dereference of freed memory.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Alexios Zavras <alexios.zavras@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Changbin Du <changbin.du@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Eric Saint-Etienne <eric.saint.etienne@oracle.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Song Liu <songliubraving@fb.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20190702103420.27540-5-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/util/annotate.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index 09762985c713..b56282041f41 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -1115,16 +1115,14 @@ static int disasm_line__parse(char *line, const char **namep, char **rawp)
*namep = strdup(name);

if (*namep == NULL)
- goto out_free_name;
+ goto out;

(*rawp)[0] = tmp;
*rawp = ltrim(*rawp);

return 0;

-out_free_name:
- free((void *)namep);
- *namep = NULL;
+out:
return -1;
}

--
2.20.1