Re: [PATCH] staging: vchiq: silence an uninitialized variable warning

2020-09-30 Thread Dan Carpenter 
On Wed, Sep 30, 2020 at 12:22:37PM +0200, Arnd Bergmann wrote:
> On Wed, Sep 30, 2020 at 11:02 AM Dan Carpenter  
> wrote:
> >
> > Smatch complains that "userdata" can be passed to vchiq_bulk_transfer()
> > without being initialized.  Smatch is correct, however, in that
> > situation the "userdata" is not used so it doesn't cause a problem.
> > Passing an uninitialized variable will trigger a UBSan warning at
> > runtime so this warning is worth silencing by setting "userdata" to
> > NULL.
> >
> > Fixes: a4367cd2b231 ("staging: vchiq: convert compat bulk transfer")
> > Signed-off-by: Dan Carpenter 
> 
> The change looks fine, but I wonder if it's actually worse and the
> uninitialized pointer can end up getting copied back to user space
> in the completion.

Ah... Wow.  You're right.  I think I really need to resend this with a
more accurate commit message.

regards,
dan carpenter


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Re: [PATCH] staging: vchiq: silence an uninitialized variable warning

2020-09-30 Thread Arnd Bergmann 
On Wed, Sep 30, 2020 at 11:02 AM Dan Carpenter  wrote:
>
> Smatch complains that "userdata" can be passed to vchiq_bulk_transfer()
> without being initialized.  Smatch is correct, however, in that
> situation the "userdata" is not used so it doesn't cause a problem.
> Passing an uninitialized variable will trigger a UBSan warning at
> runtime so this warning is worth silencing by setting "userdata" to
> NULL.
>
> Fixes: a4367cd2b231 ("staging: vchiq: convert compat bulk transfer")
> Signed-off-by: Dan Carpenter 

The change looks fine, but I wonder if it's actually worse and the
uninitialized pointer can end up getting copied back to user space
in the completion.

In either case, thanks for the fix!

Acked-by: Arnd Bergmann 
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[PATCH] staging: vchiq: silence an uninitialized variable warning

2020-09-30 Thread Dan Carpenter 
Smatch complains that "userdata" can be passed to vchiq_bulk_transfer()
without being initialized.  Smatch is correct, however, in that
situation the "userdata" is not used so it doesn't cause a problem.
Passing an uninitialized variable will trigger a UBSan warning at
runtime so this warning is worth silencing by setting "userdata" to
NULL.

Fixes: a4367cd2b231 ("staging: vchiq: convert compat bulk transfer")
Signed-off-by: Dan Carpenter 
---
 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c 
b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index 590415561b73..71b962777da5 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -952,7 +952,7 @@ static int vchiq_irq_queue_bulk_tx_rx(struct vchiq_instance 
*instance,
 {
struct vchiq_service *service;
struct bulk_waiter_node *waiter = NULL;
-   void *userdata;
+   void *userdata = NULL;
int status = 0;
int ret;
 
-- 
2.28.0

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