linux-kernel - [PATCH] perf core: Fix a bug that lead to mmap() & munmap() mismatch

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Date:	Thu, 29 Aug 2013 20:08:01 +0800
From:	Chenggang Qin <chenggang.qin@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	Chenggang Qin <chenggang.qcg@...bao.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Mike Galbraith <efault@....de>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Stephane Eranian <eranian@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Subject: [PATCH] perf core: Fix a bug that lead to mmap() & munmap() mismatch

From: Chenggang Qin <chenggang.qcg@...bao.com>

In function filename__read_debuglink(), after the elf_begin() mmapped the dso file,
the execution stream may goto "out_close". So, the elf_end() is skipped, and the
munmap() cannot be executed.

While perf is executed for a long time, the files that are not munmapped will cost
a large memory.

This patch fixed this bug.

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Mike Galbraith <efault@....de>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Signed-off-by: Chenggang Qin <chenggang.qcg@...bao.com>
---
 tools/perf/util/symbol-elf.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 4b12bf8..b4df870 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -471,27 +471,27 @@ int filename__read_debuglink(const char *filename, char *debuglink,
 
 	ek = elf_kind(elf);
 	if (ek != ELF_K_ELF)
-		goto out_close;
+		goto out_elf_end;
 
 	if (gelf_getehdr(elf, &ehdr) == NULL) {
 		pr_err("%s: cannot get elf header.\n", __func__);
-		goto out_close;
+		goto out_elf_end;
 	}
 
 	sec = elf_section_by_name(elf, &ehdr, &shdr,
 				  ".gnu_debuglink", NULL);
 	if (sec == NULL)
-		goto out_close;
+		goto out_elf_end;
 
 	data = elf_getdata(sec, NULL);
 	if (data == NULL)
-		goto out_close;
+		goto out_elf_end;
 
 	/* the start of this section is a zero-terminated string */
 	strncpy(debuglink, data->d_buf, size);
 
+out_elf_end:
 	elf_end(elf);
-
 out_close:
 	close(fd);
 out:
-- 
1.7.8.rc2.5.g815b

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