* [PATCH] of: dma_configure: Free old DMA map range
@ 2022-02-04 8:45 Mårten Lindahl
2022-02-11 14:48 ` Rob Herring
0 siblings, 1 reply; 3+ messages in thread
From: Mårten Lindahl @ 2022-02-04 8:45 UTC (permalink / raw)
To: Rob Herring, Frank Rowand; +Cc: kernel, devicetree, Mårten Lindahl
When unbinding/binding a driver with DMA mapped memory, the DMA map is
not freed when the driver is reloaded. This leads to a memory leak when
the DMA map is overwritten when reprobing the driver.
This can be reproduced with a platform driver having a dma-range:
dummy {
...
#address-cells = <0x2>;
#size-cells = <0x2>;
ranges;
dma-ranges = <...>;
...
};
and then unbinding/binding it:
~# echo soc:dummy >/sys/bus/platform/drivers/<driver>/unbind
DMA map object 0xffffff800b0ae540 still being held by &pdev->dev
~# echo soc:dummy >/sys/bus/platform/drivers/<driver>/bind
~# echo scan > /sys/kernel/debug/kmemleak
~# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffffff800b0ae540 (size 64):
comm "sh", pid 833, jiffies 4295174550 (age 2535.352s)
hex dump (first 32 bytes):
00 00 00 80 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 80 00 00 00 00 00 00 00 80 00 00 00 00 ................
backtrace:
[<ffffffefd1694708>] create_object.isra.0+0x108/0x344
[<ffffffefd1d1a850>] kmemleak_alloc+0x8c/0xd0
[<ffffffefd167e2d0>] __kmalloc+0x440/0x6f0
[<ffffffefd1a960a4>] of_dma_get_range+0x124/0x220
[<ffffffefd1a8ce90>] of_dma_configure_id+0x40/0x2d0
[<ffffffefd198b68c>] platform_dma_configure+0x5c/0xa4
[<ffffffefd198846c>] really_probe+0x8c/0x514
[<ffffffefd1988990>] __driver_probe_device+0x9c/0x19c
[<ffffffefd1988cd8>] device_driver_attach+0x54/0xbc
[<ffffffefd1986634>] bind_store+0xc4/0x120
[<ffffffefd19856e0>] drv_attr_store+0x30/0x44
[<ffffffefd173c9b0>] sysfs_kf_write+0x50/0x60
[<ffffffefd173c1c4>] kernfs_fop_write_iter+0x124/0x1b4
[<ffffffefd16a013c>] new_sync_write+0xdc/0x160
[<ffffffefd16a256c>] vfs_write+0x23c/0x2a0
[<ffffffefd16a2758>] ksys_write+0x64/0xec
Prevent overwriting the dma_range_map by freeing it before saving the
new map.
Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
---
drivers/of/device.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/of/device.c b/drivers/of/device.c
index 874f031442dc..a67703d09bfd 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -156,6 +156,12 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
kfree(map);
return -EINVAL;
}
+
+ /*
+ * Since we are about to set a new range map we should make sure we
+ * do not overwrite any existing one without having freed it first.
+ */
+ kfree(dev->dma_range_map);
}
/*
--
2.30.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] of: dma_configure: Free old DMA map range
2022-02-04 8:45 [PATCH] of: dma_configure: Free old DMA map range Mårten Lindahl
@ 2022-02-11 14:48 ` Rob Herring
2022-02-11 21:37 ` Marten Lindahl
0 siblings, 1 reply; 3+ messages in thread
From: Rob Herring @ 2022-02-11 14:48 UTC (permalink / raw)
To: Mårten Lindahl; +Cc: Frank Rowand, kernel, devicetree
On Fri, Feb 04, 2022 at 09:45:56AM +0100, Mårten Lindahl wrote:
> When unbinding/binding a driver with DMA mapped memory, the DMA map is
> not freed when the driver is reloaded. This leads to a memory leak when
> the DMA map is overwritten when reprobing the driver.
>
> This can be reproduced with a platform driver having a dma-range:
>
> dummy {
> ...
> #address-cells = <0x2>;
> #size-cells = <0x2>;
> ranges;
> dma-ranges = <...>;
> ...
> };
>
> and then unbinding/binding it:
>
> ~# echo soc:dummy >/sys/bus/platform/drivers/<driver>/unbind
>
> DMA map object 0xffffff800b0ae540 still being held by &pdev->dev
>
> ~# echo soc:dummy >/sys/bus/platform/drivers/<driver>/bind
> ~# echo scan > /sys/kernel/debug/kmemleak
> ~# cat /sys/kernel/debug/kmemleak
> unreferenced object 0xffffff800b0ae540 (size 64):
> comm "sh", pid 833, jiffies 4295174550 (age 2535.352s)
> hex dump (first 32 bytes):
> 00 00 00 80 00 00 00 00 00 00 00 00 00 00 00 00 ................
> 00 00 00 80 00 00 00 00 00 00 00 80 00 00 00 00 ................
> backtrace:
> [<ffffffefd1694708>] create_object.isra.0+0x108/0x344
> [<ffffffefd1d1a850>] kmemleak_alloc+0x8c/0xd0
> [<ffffffefd167e2d0>] __kmalloc+0x440/0x6f0
> [<ffffffefd1a960a4>] of_dma_get_range+0x124/0x220
> [<ffffffefd1a8ce90>] of_dma_configure_id+0x40/0x2d0
> [<ffffffefd198b68c>] platform_dma_configure+0x5c/0xa4
> [<ffffffefd198846c>] really_probe+0x8c/0x514
> [<ffffffefd1988990>] __driver_probe_device+0x9c/0x19c
> [<ffffffefd1988cd8>] device_driver_attach+0x54/0xbc
> [<ffffffefd1986634>] bind_store+0xc4/0x120
> [<ffffffefd19856e0>] drv_attr_store+0x30/0x44
> [<ffffffefd173c9b0>] sysfs_kf_write+0x50/0x60
> [<ffffffefd173c1c4>] kernfs_fop_write_iter+0x124/0x1b4
> [<ffffffefd16a013c>] new_sync_write+0xdc/0x160
> [<ffffffefd16a256c>] vfs_write+0x23c/0x2a0
> [<ffffffefd16a2758>] ksys_write+0x64/0xec
>
> Prevent overwriting the dma_range_map by freeing it before saving the
> new map.
>
> Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
> ---
> drivers/of/device.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/of/device.c b/drivers/of/device.c
> index 874f031442dc..a67703d09bfd 100644
> --- a/drivers/of/device.c
> +++ b/drivers/of/device.c
> @@ -156,6 +156,12 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
> kfree(map);
> return -EINVAL;
> }
> +
> + /*
> + * Since we are about to set a new range map we should make sure we
> + * do not overwrite any existing one without having freed it first.
> + */
> + kfree(dev->dma_range_map);
The map can't change, can't we just reuse the existing map. Or just bail
early? I suppose the driver could have modified the dma masks. Or the
IOMMU config could have changed.
Rob
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] of: dma_configure: Free old DMA map range
2022-02-11 14:48 ` Rob Herring
@ 2022-02-11 21:37 ` Marten Lindahl
0 siblings, 0 replies; 3+ messages in thread
From: Marten Lindahl @ 2022-02-11 21:37 UTC (permalink / raw)
To: Rob Herring
Cc: Mårten Lindahl, Frank Rowand, kernel,
devicetree@vger.kernel.org
On Fri, Feb 11, 2022 at 03:48:06PM +0100, Rob Herring wrote:
> On Fri, Feb 04, 2022 at 09:45:56AM +0100, Mårten Lindahl wrote:
> > When unbinding/binding a driver with DMA mapped memory, the DMA map is
> > not freed when the driver is reloaded. This leads to a memory leak when
> > the DMA map is overwritten when reprobing the driver.
> >
> > This can be reproduced with a platform driver having a dma-range:
> >
> > dummy {
> > ...
> > #address-cells = <0x2>;
> > #size-cells = <0x2>;
> > ranges;
> > dma-ranges = <...>;
> > ...
> > };
> >
> > and then unbinding/binding it:
> >
> > ~# echo soc:dummy >/sys/bus/platform/drivers/<driver>/unbind
> >
> > DMA map object 0xffffff800b0ae540 still being held by &pdev->dev
> >
> > ~# echo soc:dummy >/sys/bus/platform/drivers/<driver>/bind
> > ~# echo scan > /sys/kernel/debug/kmemleak
> > ~# cat /sys/kernel/debug/kmemleak
> > unreferenced object 0xffffff800b0ae540 (size 64):
> > comm "sh", pid 833, jiffies 4295174550 (age 2535.352s)
> > hex dump (first 32 bytes):
> > 00 00 00 80 00 00 00 00 00 00 00 00 00 00 00 00 ................
> > 00 00 00 80 00 00 00 00 00 00 00 80 00 00 00 00 ................
> > backtrace:
> > [<ffffffefd1694708>] create_object.isra.0+0x108/0x344
> > [<ffffffefd1d1a850>] kmemleak_alloc+0x8c/0xd0
> > [<ffffffefd167e2d0>] __kmalloc+0x440/0x6f0
> > [<ffffffefd1a960a4>] of_dma_get_range+0x124/0x220
> > [<ffffffefd1a8ce90>] of_dma_configure_id+0x40/0x2d0
> > [<ffffffefd198b68c>] platform_dma_configure+0x5c/0xa4
> > [<ffffffefd198846c>] really_probe+0x8c/0x514
> > [<ffffffefd1988990>] __driver_probe_device+0x9c/0x19c
> > [<ffffffefd1988cd8>] device_driver_attach+0x54/0xbc
> > [<ffffffefd1986634>] bind_store+0xc4/0x120
> > [<ffffffefd19856e0>] drv_attr_store+0x30/0x44
> > [<ffffffefd173c9b0>] sysfs_kf_write+0x50/0x60
> > [<ffffffefd173c1c4>] kernfs_fop_write_iter+0x124/0x1b4
> > [<ffffffefd16a013c>] new_sync_write+0xdc/0x160
> > [<ffffffefd16a256c>] vfs_write+0x23c/0x2a0
> > [<ffffffefd16a2758>] ksys_write+0x64/0xec
> >
> > Prevent overwriting the dma_range_map by freeing it before saving the
> > new map.
> >
> > Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
> > ---
> > drivers/of/device.c | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/of/device.c b/drivers/of/device.c
> > index 874f031442dc..a67703d09bfd 100644
> > --- a/drivers/of/device.c
> > +++ b/drivers/of/device.c
> > @@ -156,6 +156,12 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
> > kfree(map);
> > return -EINVAL;
> > }
> > +
> > + /*
> > + * Since we are about to set a new range map we should make sure we
> > + * do not overwrite any existing one without having freed it first.
> > + */
> > + kfree(dev->dma_range_map);
>
Hi Rob!
Thanks for looking at this.
>
> The map can't change, can't we just reuse the existing map. Or just bail
> early? I suppose the driver could have modified the dma masks. Or the
> IOMMU config could have changed.
Yes, we can reuse the existing map. I will make a check for that instead.
Kind regards
Mårten
>
> Rob
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-02-04 8:45 [PATCH] of: dma_configure: Free old DMA map range Mårten Lindahl
2022-02-11 14:48 ` Rob Herring
2022-02-11 21:37 ` Marten Lindahl
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