Re: [PATCH] ALSA: usx2y: fix a memory leak bug
On Mon, Apr 29, 2019 at 1:42 AM Takashi Iwai wrote: > > On Mon, 29 Apr 2019 07:50:11 +0200, > Wenwen Wang wrote: > > > > On Mon, Apr 29, 2019 at 12:36 AM Takashi Iwai wrote: > > > > > > On Sun, 28 Apr 2019 09:18:40 +0200, > > > Takashi Iwai wrote: > > > > > > > > On Sun, 28 Apr 2019 08:42:32 +0200, > > > > Wenwen Wang wrote: > > > > > > > > > > In usX2Y_In04_init(), a new urb is firstly created through > > > > > usb_alloc_urb() > > > > > and saved to 'usX2Y->In04urb'. Then, a buffer is allocated through > > > > > kmalloc() and saved to 'usX2Y->In04Buf'. After the urb is > > > > > initialized, a > > > > > sanity check is performed for the endpoint in the urb by invoking > > > > > usb_urb_ep_type_check(). If the check fails, the error code EINVAL > > > > > will be > > > > > returned. In that case, however, the created urb and the allocated > > > > > buffer > > > > > are not freed, leading to memory leaks. > > > > > > > > > > To fix the above issue, free the urb and the buffer if the check > > > > > fails. > > > > > > > > > > Signed-off-by: Wenwen Wang > > > > > > > > Applied now, thanks. > > > > > > ... and looking at the code again, this patch turned out to be wrong. > > > The in04 urb and transfer buffer are freed at card->private_free > > > callback (snd_usX2Y_card_private_free()) later, so this patch would > > > lead to double-free. > > > > Thanks for your comment! Does that mean we should remove > > usb_free_urb() in the if statement of allocating 'usX2Y->In04Buf', > > because it may also lead to double free? > > Yes, that's another superfluous code. Thanks! I will rework the patch. Wenwen
Re: [PATCH] ALSA: usx2y: fix a memory leak bug
On Mon, 29 Apr 2019 07:50:11 +0200, Wenwen Wang wrote: > > On Mon, Apr 29, 2019 at 12:36 AM Takashi Iwai wrote: > > > > On Sun, 28 Apr 2019 09:18:40 +0200, > > Takashi Iwai wrote: > > > > > > On Sun, 28 Apr 2019 08:42:32 +0200, > > > Wenwen Wang wrote: > > > > > > > > In usX2Y_In04_init(), a new urb is firstly created through > > > > usb_alloc_urb() > > > > and saved to 'usX2Y->In04urb'. Then, a buffer is allocated through > > > > kmalloc() and saved to 'usX2Y->In04Buf'. After the urb is initialized, a > > > > sanity check is performed for the endpoint in the urb by invoking > > > > usb_urb_ep_type_check(). If the check fails, the error code EINVAL will > > > > be > > > > returned. In that case, however, the created urb and the allocated > > > > buffer > > > > are not freed, leading to memory leaks. > > > > > > > > To fix the above issue, free the urb and the buffer if the check fails. > > > > > > > > Signed-off-by: Wenwen Wang > > > > > > Applied now, thanks. > > > > ... and looking at the code again, this patch turned out to be wrong. > > The in04 urb and transfer buffer are freed at card->private_free > > callback (snd_usX2Y_card_private_free()) later, so this patch would > > lead to double-free. > > Thanks for your comment! Does that mean we should remove > usb_free_urb() in the if statement of allocating 'usX2Y->In04Buf', > because it may also lead to double free? Yes, that's another superfluous code. Takashi
Re: [PATCH] ALSA: usx2y: fix a memory leak bug
On Mon, Apr 29, 2019 at 12:36 AM Takashi Iwai wrote: > > On Sun, 28 Apr 2019 09:18:40 +0200, > Takashi Iwai wrote: > > > > On Sun, 28 Apr 2019 08:42:32 +0200, > > Wenwen Wang wrote: > > > > > > In usX2Y_In04_init(), a new urb is firstly created through usb_alloc_urb() > > > and saved to 'usX2Y->In04urb'. Then, a buffer is allocated through > > > kmalloc() and saved to 'usX2Y->In04Buf'. After the urb is initialized, a > > > sanity check is performed for the endpoint in the urb by invoking > > > usb_urb_ep_type_check(). If the check fails, the error code EINVAL will be > > > returned. In that case, however, the created urb and the allocated buffer > > > are not freed, leading to memory leaks. > > > > > > To fix the above issue, free the urb and the buffer if the check fails. > > > > > > Signed-off-by: Wenwen Wang > > > > Applied now, thanks. > > ... and looking at the code again, this patch turned out to be wrong. > The in04 urb and transfer buffer are freed at card->private_free > callback (snd_usX2Y_card_private_free()) later, so this patch would > lead to double-free. Thanks for your comment! Does that mean we should remove usb_free_urb() in the if statement of allocating 'usX2Y->In04Buf', because it may also lead to double free? Wenwen
Re: [PATCH] ALSA: usx2y: fix a memory leak bug
On Sun, 28 Apr 2019 09:18:40 +0200, Takashi Iwai wrote: > > On Sun, 28 Apr 2019 08:42:32 +0200, > Wenwen Wang wrote: > > > > In usX2Y_In04_init(), a new urb is firstly created through usb_alloc_urb() > > and saved to 'usX2Y->In04urb'. Then, a buffer is allocated through > > kmalloc() and saved to 'usX2Y->In04Buf'. After the urb is initialized, a > > sanity check is performed for the endpoint in the urb by invoking > > usb_urb_ep_type_check(). If the check fails, the error code EINVAL will be > > returned. In that case, however, the created urb and the allocated buffer > > are not freed, leading to memory leaks. > > > > To fix the above issue, free the urb and the buffer if the check fails. > > > > Signed-off-by: Wenwen Wang > > Applied now, thanks. ... and looking at the code again, this patch turned out to be wrong. The in04 urb and transfer buffer are freed at card->private_free callback (snd_usX2Y_card_private_free()) later, so this patch would lead to double-free. I dropped the patch now. thanks, Takashi
Re: [PATCH] ALSA: usx2y: fix a memory leak bug
On Sun, 28 Apr 2019 08:42:32 +0200, Wenwen Wang wrote: > > In usX2Y_In04_init(), a new urb is firstly created through usb_alloc_urb() > and saved to 'usX2Y->In04urb'. Then, a buffer is allocated through > kmalloc() and saved to 'usX2Y->In04Buf'. After the urb is initialized, a > sanity check is performed for the endpoint in the urb by invoking > usb_urb_ep_type_check(). If the check fails, the error code EINVAL will be > returned. In that case, however, the created urb and the allocated buffer > are not freed, leading to memory leaks. > > To fix the above issue, free the urb and the buffer if the check fails. > > Signed-off-by: Wenwen Wang Applied now, thanks. Takashi
