Question on verify_area() and friends wrt

[Paulo Andre' (l16083@alunos.uevora.pt)]

Hi,

I've been taking care of auditing some return values for instances of
unchecked copy_*_user calls and I've come across one case that's
marked as a bug at kbugs.org which however doesn't seem like one to me.
The piece of code I'm referring can be found in
net/bluetooth/hci_core.c:436

if (!verify_area(VERIFY_WRITE, ptr, sizeof(ir) +
		(sizeof(struct inquiry_info) * ir.num_rsp))) {
    copy_to_user(ptr, &ir, sizeof(ir));
    ptr += sizeof(ir);
    copy_to_user(ptr, buf, sizeof(struct inquiry_info) * ir.num_rsp);	} else
    err = -EFAULT;

I'm presuming verify_area() does its job fine returning 0 if the memory
is valid and -EFAULT if not. Thus, given the exact check that's been
done, there seems indeed to exist no need to check each call to
copy_to_user() below. Or is there?

Thanks in advance,


		Paulo
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