* [PATCH] dma: Fix a double free in dma_async_device_register
@ 2021-03-22 13:08 Lv Yunlong
0 siblings, 0 replies; 3+ messages in thread
From: Lv Yunlong @ 2021-03-22 13:08 UTC (permalink / raw)
To: vkoul; +Cc: dmaengine, linux-kernel, Lv Yunlong
In dma_async_device_register, in the loop
list_for_each_entry(chan, &device->channels, device_node).
If __dma_async_device_channel_register(device, chan) failed
and it colud free chan->local and return err.
But in the err_out branch, it will free chan->local again.
My patch sets chan->local to NULL after it is freed in
__dma_async_device_channel_register().
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
---
drivers/dma/dmaengine.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index fe6a460c4373..af3ee288bc11 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -1086,6 +1086,7 @@ static int __dma_async_device_channel_register(struct dma_device *device,
kfree(chan->dev);
err_free_local:
free_percpu(chan->local);
+ chan->local = NULL;
return rc;
}
--
2.25.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH] dma: Fix a double free in dma_async_device_register
@ 2021-03-30 9:01 Lv Yunlong
2021-03-30 16:05 ` Dave Jiang
0 siblings, 1 reply; 3+ messages in thread
From: Lv Yunlong @ 2021-03-30 9:01 UTC (permalink / raw)
To: vkoul, dave.jiang; +Cc: dmaengine, linux-kernel, Lv Yunlong
In the first list_for_each_entry() macro of dma_async_device_register,
it gets the chan from list and calls __dma_async_device_channel_register
(..,chan). We can see that chan->local is allocated by alloc_percpu() and
it is freed chan->local by free_percpu(chan->local) when
__dma_async_device_channel_register() failed.
But after __dma_async_device_channel_register() failed, the caller will
goto err_out and freed the chan->local in the second time by free_percpu().
The cause of this problem is forget to set chan->local to NULL when
chan->local was freed in __dma_async_device_channel_register(). My
patch sets chan->local to NULL when the callee failed to avoid double free.
Fixes: d2fb0a0438384 ("dmaengine: break out channel registration")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
---
drivers/dma/dmaengine.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index fe6a460c4373..fef64b198c95 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -1249,8 +1249,10 @@ int dma_async_device_register(struct dma_device *device)
/* represent channels in sysfs. Probably want devs too */
list_for_each_entry(chan, &device->channels, device_node) {
rc = __dma_async_device_channel_register(device, chan);
- if (rc < 0)
+ if (rc < 0) {
+ chan->local = NULL;
goto err_out;
+ }
}
mutex_lock(&dma_list_mutex);
--
2.25.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] dma: Fix a double free in dma_async_device_register
2021-03-30 9:01 Lv Yunlong
@ 2021-03-30 16:05 ` Dave Jiang
0 siblings, 0 replies; 3+ messages in thread
From: Dave Jiang @ 2021-03-30 16:05 UTC (permalink / raw)
To: Lv Yunlong, vkoul; +Cc: dmaengine, linux-kernel
On 3/30/2021 2:01 AM, Lv Yunlong wrote:
> In the first list_for_each_entry() macro of dma_async_device_register,
> it gets the chan from list and calls __dma_async_device_channel_register
> (..,chan). We can see that chan->local is allocated by alloc_percpu() and
> it is freed chan->local by free_percpu(chan->local) when
> __dma_async_device_channel_register() failed.
>
> But after __dma_async_device_channel_register() failed, the caller will
> goto err_out and freed the chan->local in the second time by free_percpu().
>
> The cause of this problem is forget to set chan->local to NULL when
> chan->local was freed in __dma_async_device_channel_register(). My
> patch sets chan->local to NULL when the callee failed to avoid double free.
Thanks for the fix. I think it would make sense to set it to NULL in
__dma_async_device_channel_register() cleanup path after it calls
free_percpu(chan->local) right? That would address any other instances
of this issue happening else where.
>
> Fixes: d2fb0a0438384 ("dmaengine: break out channel registration")
> Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
> ---
> drivers/dma/dmaengine.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index fe6a460c4373..fef64b198c95 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -1249,8 +1249,10 @@ int dma_async_device_register(struct dma_device *device)
> /* represent channels in sysfs. Probably want devs too */
> list_for_each_entry(chan, &device->channels, device_node) {
> rc = __dma_async_device_channel_register(device, chan);
> - if (rc < 0)
> + if (rc < 0) {
> + chan->local = NULL;
> goto err_out;
> + }
> }
>
> mutex_lock(&dma_list_mutex);
^ permalink raw reply [flat|nested] 3+ messages in thread
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