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clk: Fix memory leak in clk_unregister()

PATCH Applied Kishon Vijay Abraham I 2 participants 5 messages Oct 22, 2019 – Nov 19, 2019 Common clk

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Kishon Vijay Abraham I

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#0 lore raw

PATCH 1/1 clk: Fix memory leak in clk_unregister()

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 <[email protected]>
Cc Tero Kristo <[email protected]>
Signed-off-by Kishon Vijay Abraham I <[email protected]>
---
 drivers/clk/clk.c | 1 +
 1 file changed, 1 insertion(+)
drivers/clk/clk.c +1 -0
index 1c677d7f7f53..2f2eea26c375 100644
@@ -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();
 }
Signature · 1 line
2.17.1
maintainer
#1 lore raw

Quoting Kishon Vijay Abraham I (2019-10-22 00:11:53)

Quoted 23 lines

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
Quoted 1 line

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!

author
#2 lore raw

PATCH v2 1/1 clk: Fix memory leak in clk_unregister()

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 <[email protected]>
Cc Tero Kristo <[email protected]>
Signed-off-by Kishon Vijay Abraham I <[email protected]>
---
 drivers/clk/clk.c | 4 ++++
 1 file changed, 4 insertions(+)
drivers/clk/clk.c +4 -0
index 1c677d7f7f53..ecd647258c8f 100644
@@ -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();
 }
Signature · 1 line
2.17.1
author
#3 lore raw

Hi Stephen,

Quoted 23 lines · 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
Quoted 6 lines

Fix it here.

Fixes fcb0ee6a3d331fb ("clk: Implement clk_unregister")
Cc Tomi Valkeinen <[email protected]>
Cc Tero Kristo <[email protected]>
Signed-off-by Kishon Vijay Abraham I <[email protected]>

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

Thanks
Kishon

Quoted 27 lines
---
 drivers/clk/clk.c | 4 ++++
 1 file changed, 4 insertions(+)
drivers/clk/clk.c +4 -0
index 1c677d7f7f53..ecd647258c8f 100644
@@ -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();
 }
maintainer Applied
#4 lore raw
In reply to Kishon Vijay Abraham I

Quoting Kishon Vijay Abraham I (2019-10-22 00:11:53)

Quoted 23 lines

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
Quoted 6 lines

Fix it here.

Cc Tomi Valkeinen <[email protected]>
Cc Tero Kristo <[email protected]>
Signed-off-by Kishon Vijay Abraham I <[email protected]>

---

Applied to clk-next

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