[PATCH] clk: Fix memory leak in clk_unregister()

[PATCH] clk: Fix memory leak in clk_unregister()

[Kishon Vijay Abraham I]

Memory allocated in alloc_clk() for 'struct clk' and
'const char *con_id' while invoking clk_register() is never freed
in clk_unregister(), resulting in kmemleak showing the following
backtrace.

  backtrace:
    [<00000000546f5dd0>] kmem_cache_alloc+0x18c/0x270
    [<0000000073a32862>] alloc_clk+0x30/0x70
    [<0000000082942480>] __clk_register+0xc8/0x760
    [<000000005c859fca>] devm_clk_register+0x54/0xb0
    [<00000000868834a8>] 0xffff800008c60950
    [<00000000d5a80534>] platform_drv_probe+0x50/0xa0
    [<000000001b3889fc>] really_probe+0x108/0x348
    [<00000000953fa60a>] driver_probe_device+0x58/0x100
    [<0000000008acc17c>] device_driver_attach+0x6c/0x90
    [<0000000022813df3>] __driver_attach+0x84/0xc8
    [<00000000448d5443>] bus_for_each_dev+0x74/0xc8
    [<00000000294aa93f>] driver_attach+0x20/0x28
    [<00000000e5e52626>] bus_add_driver+0x148/0x1f0
    [<000000001de21efc>] driver_register+0x60/0x110
    [<00000000af07c068>] __platform_driver_register+0x40/0x48
    [<0000000060fa80ee>] 0xffff800008c66020

Fix it here.

Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
---
 drivers/clk/clk.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 1c677d7f7f53..2f2eea26c375 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -3879,6 +3879,7 @@ void clk_unregister(struct clk *clk)
 					__func__, clk->core->name);
 
 	kref_put(&clk->core->ref, __clk_release);
+	free_clk(clk);
 unlock:
 	clk_prepare_unlock();
 }
-- 
2.17.1

Re: [PATCH] clk: Fix memory leak in clk_unregister()

[Stephen Boyd]

Quoting Kishon Vijay Abraham I (2019-10-22 00:11:53)
> Memory allocated in alloc_clk() for 'struct clk' and
> 'const char *con_id' while invoking clk_register() is never freed
> in clk_unregister(), resulting in kmemleak showing the following
> backtrace.
> 
>   backtrace:
>     [<00000000546f5dd0>] kmem_cache_alloc+0x18c/0x270
>     [<0000000073a32862>] alloc_clk+0x30/0x70
>     [<0000000082942480>] __clk_register+0xc8/0x760
>     [<000000005c859fca>] devm_clk_register+0x54/0xb0
>     [<00000000868834a8>] 0xffff800008c60950
>     [<00000000d5a80534>] platform_drv_probe+0x50/0xa0
>     [<000000001b3889fc>] really_probe+0x108/0x348
>     [<00000000953fa60a>] driver_probe_device+0x58/0x100
>     [<0000000008acc17c>] device_driver_attach+0x6c/0x90
>     [<0000000022813df3>] __driver_attach+0x84/0xc8
>     [<00000000448d5443>] bus_for_each_dev+0x74/0xc8
>     [<00000000294aa93f>] driver_attach+0x20/0x28
>     [<00000000e5e52626>] bus_add_driver+0x148/0x1f0
>     [<000000001de21efc>] driver_register+0x60/0x110
>     [<00000000af07c068>] __platform_driver_register+0x40/0x48
>     [<0000000060fa80ee>] 0xffff800008c66020
> 
> Fix it here.

Do you have some Fixes tag for this? Looks OK to me, but I wonder if we
should also assign hw->clk to NULL after unregister frees it. There are
probably other problems around unregistration and reference counting
that we haven't found so far so I'm worried this doesn't solve all the
problems by just freeing the clk pointer.

For example, anything referencing the clk pointer freed here will now
start trying to dereference freed memory. For most cases we've replaced
struct clk with struct clk_core in the clk framework so I hope this
pointer isn't used very much at all. A quick grep shows that it is
returned from clk_get_parent() and __clk_lookup(). We really need to
kill off __clk_lookup() and replace it with something else, and
clk_get_parent() needs to generate a different clk and have callers call
clk_put() on the returned pointer. Long story short I think this is OK!

[PATCH v2] clk: Fix memory leak in clk_unregister()

[Kishon Vijay Abraham I]

Memory allocated in alloc_clk() for 'struct clk' and
'const char *con_id' while invoking clk_register() is never freed
in clk_unregister(), resulting in kmemleak showing the following
backtrace.

  backtrace:
    [<00000000546f5dd0>] kmem_cache_alloc+0x18c/0x270
    [<0000000073a32862>] alloc_clk+0x30/0x70
    [<0000000082942480>] __clk_register+0xc8/0x760
    [<000000005c859fca>] devm_clk_register+0x54/0xb0
    [<00000000868834a8>] 0xffff800008c60950
    [<00000000d5a80534>] platform_drv_probe+0x50/0xa0
    [<000000001b3889fc>] really_probe+0x108/0x348
    [<00000000953fa60a>] driver_probe_device+0x58/0x100
    [<0000000008acc17c>] device_driver_attach+0x6c/0x90
    [<0000000022813df3>] __driver_attach+0x84/0xc8
    [<00000000448d5443>] bus_for_each_dev+0x74/0xc8
    [<00000000294aa93f>] driver_attach+0x20/0x28
    [<00000000e5e52626>] bus_add_driver+0x148/0x1f0
    [<000000001de21efc>] driver_register+0x60/0x110
    [<00000000af07c068>] __platform_driver_register+0x40/0x48
    [<0000000060fa80ee>] 0xffff800008c66020

Fix it here.

Fixes: fcb0ee6a3d331fb ("clk: Implement clk_unregister")
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
---
 drivers/clk/clk.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 1c677d7f7f53..ecd647258c8f 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -3835,6 +3835,7 @@ static void clk_core_evict_parent_cache(struct clk_core *core)
 void clk_unregister(struct clk *clk)
 {
 	unsigned long flags;
+	struct clk_hw *hw;
 
 	if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
 		return;
@@ -3879,6 +3880,9 @@ void clk_unregister(struct clk *clk)
 					__func__, clk->core->name);
 
 	kref_put(&clk->core->ref, __clk_release);
+	hw = clk->core->hw;
+	free_clk(clk);
+	hw->clk = NULL;
 unlock:
 	clk_prepare_unlock();
 }
-- 
2.17.1

Re: [PATCH v2] clk: Fix memory leak in clk_unregister()

[Kishon Vijay Abraham I]

Hi Stephen,

On 29/10/19 4:36 PM, Kishon Vijay Abraham I wrote:
> Memory allocated in alloc_clk() for 'struct clk' and
> 'const char *con_id' while invoking clk_register() is never freed
> in clk_unregister(), resulting in kmemleak showing the following
> backtrace.
> 
>   backtrace:
>     [<00000000546f5dd0>] kmem_cache_alloc+0x18c/0x270
>     [<0000000073a32862>] alloc_clk+0x30/0x70
>     [<0000000082942480>] __clk_register+0xc8/0x760
>     [<000000005c859fca>] devm_clk_register+0x54/0xb0
>     [<00000000868834a8>] 0xffff800008c60950
>     [<00000000d5a80534>] platform_drv_probe+0x50/0xa0
>     [<000000001b3889fc>] really_probe+0x108/0x348
>     [<00000000953fa60a>] driver_probe_device+0x58/0x100
>     [<0000000008acc17c>] device_driver_attach+0x6c/0x90
>     [<0000000022813df3>] __driver_attach+0x84/0xc8
>     [<00000000448d5443>] bus_for_each_dev+0x74/0xc8
>     [<00000000294aa93f>] driver_attach+0x20/0x28
>     [<00000000e5e52626>] bus_add_driver+0x148/0x1f0
>     [<000000001de21efc>] driver_register+0x60/0x110
>     [<00000000af07c068>] __platform_driver_register+0x40/0x48
>     [<0000000060fa80ee>] 0xffff800008c66020
> 
> Fix it here.
> 
> Fixes: fcb0ee6a3d331fb ("clk: Implement clk_unregister")
> Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Cc: Tero Kristo <t-kristo@ti.com>
> Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

Ignore the v2 of this patch. Sent this patch a bit early. Sorry for the noise.

Thanks
Kishon
> ---
>  drivers/clk/clk.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 1c677d7f7f53..ecd647258c8f 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -3835,6 +3835,7 @@ static void clk_core_evict_parent_cache(struct clk_core *core)
>  void clk_unregister(struct clk *clk)
>  {
>  	unsigned long flags;
> +	struct clk_hw *hw;
>  
>  	if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
>  		return;
> @@ -3879,6 +3880,9 @@ void clk_unregister(struct clk *clk)
>  					__func__, clk->core->name);
>  
>  	kref_put(&clk->core->ref, __clk_release);
> +	hw = clk->core->hw;
> +	free_clk(clk);
> +	hw->clk = NULL;
>  unlock:
>  	clk_prepare_unlock();
>  }
> 

Re: [PATCH] clk: Fix memory leak in clk_unregister()

[Stephen Boyd]

Quoting Kishon Vijay Abraham I (2019-10-22 00:11:53)
> Memory allocated in alloc_clk() for 'struct clk' and
> 'const char *con_id' while invoking clk_register() is never freed
> in clk_unregister(), resulting in kmemleak showing the following
> backtrace.
> 
>   backtrace:
>     [<00000000546f5dd0>] kmem_cache_alloc+0x18c/0x270
>     [<0000000073a32862>] alloc_clk+0x30/0x70
>     [<0000000082942480>] __clk_register+0xc8/0x760
>     [<000000005c859fca>] devm_clk_register+0x54/0xb0
>     [<00000000868834a8>] 0xffff800008c60950
>     [<00000000d5a80534>] platform_drv_probe+0x50/0xa0
>     [<000000001b3889fc>] really_probe+0x108/0x348
>     [<00000000953fa60a>] driver_probe_device+0x58/0x100
>     [<0000000008acc17c>] device_driver_attach+0x6c/0x90
>     [<0000000022813df3>] __driver_attach+0x84/0xc8
>     [<00000000448d5443>] bus_for_each_dev+0x74/0xc8
>     [<00000000294aa93f>] driver_attach+0x20/0x28
>     [<00000000e5e52626>] bus_add_driver+0x148/0x1f0
>     [<000000001de21efc>] driver_register+0x60/0x110
>     [<00000000af07c068>] __platform_driver_register+0x40/0x48
>     [<0000000060fa80ee>] 0xffff800008c66020
> 
> Fix it here.
> 
> Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Cc: Tero Kristo <t-kristo@ti.com>
> Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
> ---

Applied to clk-next

I also added a fixes tag for the best I could guess.