linux-kernel - [PATCH 1/3] perf core: Fix a mmap and munmap mismatched bug

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Date:	Sun,  1 Sep 2013 23:29:43 +0800
From:	Chenggang Qin <chenggang.qin@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	root <root@...e097011.sqa.cm4>, David Ahern <dsahern@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Namhyung Kim <namhyung@...il.com>,
	Yanmin Zhang <yanmin.zhang@...el.com>,
	Wu Fengguang <fengguang.wu@...el.com>,
	Mike Galbraith <efault@....de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Chenggang Qin <chenggang.qcg@...bao.com>
Subject: [PATCH 1/3] perf core: Fix a mmap and munmap mismatched bug

From: root <root@...e097011.sqa.cm4>

In function filename__read_debuglink(), while the ELF file is opend and mmapped
in elf_begin(), but if this file is considered to not be usable during the
following code, we will goto the close(fd) directly. The elf_end() is skipped.
So, the mmaped ELF file cannot be munmapped. The memory areas are mmapped is
exist during the life of perf. This is a memory leak.
This patch fixed this bug.
Thanks.

Cc: David Ahern <dsahern@...il.com>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc: Arjan van de Ven <arjan@...ux.intel.com>
Cc: Namhyung Kim <namhyung@...il.com>
Cc: Yanmin Zhang <yanmin.zhang@...el.com>
Cc: Wu Fengguang <fengguang.wu@...el.com>
Cc: Mike Galbraith <efault@....de>
Cc: Andrew Morton <akpm@...ux-foundation.org>
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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