[PATCH 3.14 214/228] clk: Fix double free due to devm_clk_register()

Greg Kroah-Hartman
2014-06-04T23:54:10Z

From: Stephen Boyd <sboyd@codeaurora.org>

commit 293ba3b4a4fd54891b900f2911d1a57e1ed4a843 upstream.

Now that clk_unregister() frees the struct clk we're
unregistering we'll free memory twice: first we'll call kfree()
in __clk_release() with an address kmalloc doesn't know about and
second we'll call kfree() in the devres layer. Remove the
allocation of struct clk in devm_clk_register() and let
clk_release() handle it. This fixes slab errors like:

=============================================================================
BUG kmalloc-128 (Not tainted): Invalid object pointer 0xed08e8d0
-----------------------------------------------------------------------------

Disabling lock debugging due to kernel taint
INFO: Slab 0xeec503f8 objects=25 used=15 fp=0xed08ea00 flags=0x4081
CPU: 2 PID: 73 Comm: rmmod Tainted: G B 3.14.0-11032-g526e9c764381 #34
[<c0014be0>] (unwind_backtrace) from [<c0012240>] (show_stack+0x10/0x14)
[<c0012240>] (show_stack) from [<c04b74dc>] (dump_stack+0x70/0xbc)
[<c04b74dc>] (dump_stack) from [<c00f6778>] (slab_err+0x74/0x84)
[<c00f6778>] (slab_err) from [<c04b6278>] (free_debug_processing+0x2cc/0x31c)
[<c04b6278>] (free_debug_processing) from [<c04b6300>] (__slab_free+0x38/0x41c)
[<c04b6300>] (__slab_free) from [<c03931bc>] (clk_unregister+0xd4/0x140)
[<c03931bc>] (clk_unregister) from [<c02fb774>] (release_nodes+0x164/0x1d8)
[<c02fb774>] (release_nodes) from [<c02f8698>] (__device_release_driver+0x60/0xb0)
[<c02f8698>] (__device_release_driver) from [<c02f9080>] (driver_detach+0xb4/0xb8)
[<c02f9080>] (driver_detach) from [<c02f8480>] (bus_remove_driver+0x5c/0xc4)
[<c02f8480>] (bus_remove_driver) from [<c008c9b8>] (SyS_delete_module+0x148/0x1d8)
[<c008c9b8>] (SyS_delete_module) from [<c000ef80>] (ret_fast_syscall+0x0/0x48)
FIX kmalloc-128: Object at 0xed08e8d0 not freed

Fixes: fcb0ee6a3d33 (clk: Implement clk_unregister)
Cc: Jiada Wang <jiada_wang@mentor.com>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/clk/clk.c | 71 ++++++++++++++++++++++--------------------------------
1 file changed, 30 insertions(+), 41 deletions(-)

--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1977,9 +1977,28 @@ struct clk *__clk_register(struct device
}
EXPORT_SYMBOL_GPL(__clk_register);

-static int _clk_register(struct device *dev, struct clk_hw *hw, struct clk *clk)
+/**
+ * clk_register - allocate a new clock, register it and return an opaque cookie
+ * @dev: device that is registering this clock
+ * @hw: link to hardware-specific clock data
+ *
+ * clk_register is the primary interface for populating the clock tree with new
+ * clock nodes. It returns a pointer to the newly allocated struct clk which
+ * cannot be dereferenced by driver code but may be used in conjuction with the
+ * rest of the clock API. In the event of an error clk_register will return an
+ * error code; drivers must test for an error code after calling clk_register.
+ */
+struct clk *clk_register(struct device *dev, struct clk_hw *hw)
{
int i, ret;
+ struct clk *clk;
+
+ clk = kzalloc(sizeof(*clk), GFP_KERNEL);
+ if (!clk) {
+ pr_err("%s: could not allocate clk\n", __func__);
+ ret = -ENOMEM;
+ goto fail_out;
+ }

clk->name = kstrdup(hw->init->name, GFP_KERNEL);
if (!clk->name) {
@@ -2019,7 +2038,7 @@ static int _clk_register(struct device *

ret = __clk_init(dev, clk);
if (!ret)
- return 0;
+ return clk;

fail_parent_names_copy:
while (--i >= 0)
@@ -2028,36 +2047,6 @@ fail_parent_names_copy:
fail_parent_names:
kfree(clk->name);
fail_name:
- return ret;
-}
-
-/**
- * clk_register - allocate a new clock, register it and return an opaque cookie
- * @dev: device that is registering this clock
- * @hw: link to hardware-specific clock data
- *
- * clk_register is the primary interface for populating the clock tree with new
- * clock nodes. It returns a pointer to the newly allocated struct clk which
- * cannot be dereferenced by driver code but may be used in conjuction with the
- * rest of the clock API. In the event of an error clk_register will return an
- * error code; drivers must test for an error code after calling clk_register.
- */
-struct clk *clk_register(struct device *dev, struct clk_hw *hw)
-{
- int ret;
- struct clk *clk;
-
- clk = kzalloc(sizeof(*clk), GFP_KERNEL);
- if (!clk) {
- pr_err("%s: could not allocate clk\n", __func__);
- ret = -ENOMEM;
- goto fail_out;
- }
-
- ret = _clk_register(dev, hw, clk);
- if (!ret)
- return clk;
-
kfree(clk);
fail_out:
return ERR_PTR(ret);
@@ -2166,7 +2155,7 @@ EXPORT_SYMBOL_GPL(clk_unregister);

static void devm_clk_release(struct device *dev, void *res)
{
- clk_unregister(res);
+ clk_unregister(*(struct clk **)res);
}

/**
@@ -2181,18 +2170,18 @@ static void devm_clk_release(struct devi
struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw)
{
struct clk *clk;
- int ret;
+ struct clk **clkp;

- clk = devres_alloc(devm_clk_release, sizeof(*clk), GFP_KERNEL);
- if (!clk)
+ clkp = devres_alloc(devm_clk_release, sizeof(*clkp), GFP_KERNEL);
+ if (!clkp)
return ERR_PTR(-ENOMEM);

- ret = _clk_register(dev, hw, clk);
- if (!ret) {
- devres_add(dev, clk);
+ clk = clk_register(dev, hw);
+ if (!IS_ERR(clk)) {
+ *clkp = clk;
+ devres_add(dev, clkp);
} else {
- devres_free(clk);
- clk = ERR_PTR(ret);
+ devres_free(clkp);
}

return clk;