linux-kernel - [PATCH] regmap: debugfs: Fix memory leak in regmap_debugfs

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Message-ID: <20190517132324.23603-1-daniel.baluta@nxp.com>
Date:   Fri, 17 May 2019 13:23:49 +0000
From:   Daniel Baluta <daniel.baluta@....com>
To:     "broonie@...nel.org" <broonie@...nel.org>
CC:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "rafael@...nel.org" <rafael@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "stefan.wahren@...e.com" <stefan.wahren@...e.com>,
        Daniel Baluta <daniel.baluta@....com>
Subject: [PATCH] regmap: debugfs: Fix memory leak in regmap_debugfs_init

As detected by kmemleak running on i.MX6ULL board:

nreferenced object 0xd8366600 (size 64):
  comm "swapper/0", pid 1, jiffies 4294937370 (age 933.220s)
  hex dump (first 32 bytes):
    64 75 6d 6d 79 2d 69 6f 6d 75 78 63 2d 67 70 72  dummy-iomuxc-gpr
    40 32 30 65 34 30 30 30 00 e3 f3 ab fe d1 1b dd  @20e4000........
  backtrace:
    [<b0402aec>] kasprintf+0x2c/0x54
    [<a6fbad2c>] regmap_debugfs_init+0x7c/0x31c
    [<9c8d91fa>] __regmap_init+0xb5c/0xcf4
    [<5b1c3d2a>] of_syscon_register+0x164/0x2c4
    [<596a5d80>] syscon_node_to_regmap+0x64/0x90
    [<49bd597b>] imx6ul_init_machine+0x34/0xa0
    [<250a4dac>] customize_machine+0x1c/0x30
    [<2d19fdaf>] do_one_initcall+0x7c/0x398
    [<e6084469>] kernel_init_freeable+0x328/0x448
    [<168c9101>] kernel_init+0x8/0x114
    [<913268aa>] ret_from_fork+0x14/0x20
    [<ce7b131a>] 0x0

Root cause is that map->debugfs_name is allocated using kasprintf
and then the pointer is lost by assigning it other memory address.

Reported-by: Stefan Wahren <stefan.wahren@...e.com>
Signed-off-by: Daniel Baluta <daniel.baluta@....com>
---
 drivers/base/regmap/regmap-debugfs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index 263f82516ff4..e5e1b3a01b1a 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -579,6 +579,8 @@ void regmap_debugfs_init(struct regmap *map, const char *name)
 	}
 
 	if (!strcmp(name, "dummy")) {
+		kfree(map->debugfs_name);
+
 		map->debugfs_name = kasprintf(GFP_KERNEL, "dummy%d",
 						dummy_index);
 		name = map->debugfs_name;
-- 
2.17.1