RE: [PATCH] usb: gadget: acm: set notify_req to NULL after freed to avoid double free

[Du, Changbin]

> On 12/26/2015 04:57 AM, changbin...@intel.com wrote:
> > From: "Du, Changbin" 
> >
> > If acm_bind fails before allocate notification and acm->notify_req is
> > not set to NULL after freed last time, double free will happen.
> 
> Looks good to me.
> 
> Similar problem can occur with another USB functions (at least f_ecm,
> f_ncm, f_rndis and f_hid handle USB requests in analogical way). Maybe
> it's worth to fix them all at once?
> 
> >
> > kernel BUG at mm/slub.c:3392!
> > invalid opcode:  [#1] PREEMPT SMP
> > EIP is at kfree+0x172/0x180
> > Call Trace:
> > [<80c0e3b6>] ? usb_ep_autoconfig_ss+0x86/0x170
> > [<80c13345>] gs_free_req+0x15/0x30
> > [<80c12df1>] acm_bind+0x1c1/0x2d0
> > [<80c0e9be>] usb_add_function+0x6e/0x120
> > [<80c213cb>] acm_function_bind_config+0x2b/0x90
> >
> 
> Reviewed-by: Robert Baldyga 
>
Hmm, you are right. I checked all the fucntions, found these need to be fixed:
f_ecm.c f_hid.c f_ncm.c f_phonet.c f_rndis.c f_uvc.c

I will update patche to fix them all. thank you.

Regards,
Du, Changbin

Re: [PATCH] usb: gadget: acm: set notify_req to NULL after freed to avoid double free

[Robert Baldyga]

On 12/26/2015 04:57 AM, changbin...@intel.com wrote:
> From: "Du, Changbin" 
> 
> If acm_bind fails before allocate notification and acm->notify_req is
> not set to NULL after freed last time, double free will happen.

Looks good to me.

Similar problem can occur with another USB functions (at least f_ecm,
f_ncm, f_rndis and f_hid handle USB requests in analogical way). Maybe
it's worth to fix them all at once?

> 
> kernel BUG at mm/slub.c:3392!
> invalid opcode:  [#1] PREEMPT SMP
> EIP is at kfree+0x172/0x180
> Call Trace:
> [<80c0e3b6>] ? usb_ep_autoconfig_ss+0x86/0x170
> [<80c13345>] gs_free_req+0x15/0x30
> [<80c12df1>] acm_bind+0x1c1/0x2d0
> [<80c0e9be>] usb_add_function+0x6e/0x120
> [<80c213cb>] acm_function_bind_config+0x2b/0x90
> 

Reviewed-by: Robert Baldyga 

> Signed-off-by: Du, Changbin 
> ---
>  drivers/usb/gadget/function/f_acm.c | 8 ++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/gadget/function/f_acm.c 
> b/drivers/usb/gadget/function/f_acm.c
> index 2fa1e80..e10c8d4 100644
> --- a/drivers/usb/gadget/function/f_acm.c
> +++ b/drivers/usb/gadget/function/f_acm.c
> @@ -699,8 +699,10 @@ acm_bind(struct usb_configuration *c, struct 
> usb_function *f)
>   return 0;
>  
>  fail:
> - if (acm->notify_req)
> + if (acm->notify_req) {
>   gs_free_req(acm->notify, acm->notify_req);
> + acm->notify_req = NULL;
> + }
>  
>   ERROR(cdev, "%s/%p: can't bind, err %d\n", f->name, f, status);
>  
> @@ -713,8 +715,10 @@ static void acm_unbind(struct usb_configuration *c, 
> struct usb_function *f)
>  
>   acm_string_defs[0].id = 0;
>   usb_free_all_descriptors(f);
> - if (acm->notify_req)
> + if (acm->notify_req) {
>   gs_free_req(acm->notify, acm->notify_req);
> + acm->notify_req = NULL;
> + }
>  }
>  
>  static void acm_free_func(struct usb_function *f)
> 


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[PATCH] usb: gadget: acm: set notify_req to NULL after freed to avoid double free

[changbin . du]

From: "Du, Changbin" 

If acm_bind fails before allocate notification and acm->notify_req is
not set to NULL after freed last time, double free will happen.

kernel BUG at mm/slub.c:3392!
invalid opcode:  [#1] PREEMPT SMP
EIP is at kfree+0x172/0x180
Call Trace:
[<80c0e3b6>] ? usb_ep_autoconfig_ss+0x86/0x170
[<80c13345>] gs_free_req+0x15/0x30
[<80c12df1>] acm_bind+0x1c1/0x2d0
[<80c0e9be>] usb_add_function+0x6e/0x120
[<80c213cb>] acm_function_bind_config+0x2b/0x90

Signed-off-by: Du, Changbin 
---
 drivers/usb/gadget/function/f_acm.c | 8 ++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/f_acm.c 
b/drivers/usb/gadget/function/f_acm.c
index 2fa1e80..e10c8d4 100644
--- a/drivers/usb/gadget/function/f_acm.c
+++ b/drivers/usb/gadget/function/f_acm.c
@@ -699,8 +699,10 @@ acm_bind(struct usb_configuration *c, struct usb_function 
*f)
return 0;
 
 fail:
-   if (acm->notify_req)
+   if (acm->notify_req) {
gs_free_req(acm->notify, acm->notify_req);
+   acm->notify_req = NULL;
+   }
 
ERROR(cdev, "%s/%p: can't bind, err %d\n", f->name, f, status);
 
@@ -713,8 +715,10 @@ static void acm_unbind(struct usb_configuration *c, struct 
usb_function *f)
 
acm_string_defs[0].id = 0;
usb_free_all_descriptors(f);
-   if (acm->notify_req)
+   if (acm->notify_req) {
gs_free_req(acm->notify, acm->notify_req);
+   acm->notify_req = NULL;
+   }
 }
 
 static void acm_free_func(struct usb_function *f)
-- 
2.5.0

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