Messages in this thread | | | Subject | Re: [PATCH] staging: vchiq_arm: Using copy_from_user() to copy data from userspace address | From | Phi Nguyen <> | Date | Tue, 25 May 2021 01:26:23 +0800 |
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On 22/5/21 2:33 pm, Al Viro wrote: > On Sat, May 22, 2021 at 01:34:29PM +0800, Nguyen Dinh Phi wrote: >> This commit to fix the following sparse warning: >> incorrect type in assignment (different address spaces) >> expected void *[assigned] userdata >> got void [noderef] __user *userdata >> >> Signed-off-by: Nguyen Dinh Phi <phind.uet@gmail.com> >> --- >> .../staging/vc04_services/interface/vchiq_arm/vchiq_arm.c | 5 ++++- >> 1 file changed, 4 insertions(+), 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 afbf01b7364c..2a4fc599f977 100644 >> --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c >> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c >> @@ -960,7 +960,10 @@ static int vchiq_irq_queue_bulk_tx_rx(struct vchiq_instance *instance, >> current->pid); >> userdata = &waiter->bulk_waiter; >> } else { >> - userdata = args->userdata; >> + if (copy_from_user(userdata, args->userdata, sizeof(args->userdata))) { > > The contents of userdata (local variable of type void *) is uninitialized at that > point. Sorry, That was my mistake.
> Just what do you think that call of copy_from_user() would do?
Because according to the definition of struct vchiq_queue_bulk_transfer, the args->userdata pointer is userspace address.
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