Re: [PATCH] tty:vt: Add check the return value of kzalloc to avoid oops

[Nicolas Pitre]

On Thu, 19 Sep 2019, Greg KH wrote:

> On Thu, Sep 19, 2019 at 05:18:15PM +0800, Xiaoming Ni wrote:
> > Using kzalloc() to allocate memory in function con_init(), but not
> > checking the return value, there is a risk of null pointer references
> > oops.
> > 
> > Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
> 
> We keep having this be "reported" :(

Something probably needs to be "communicated" about that.

> >  		vc_cons[currcons].d = vc = kzalloc(sizeof(struct vc_data), GFP_NOWAIT);
> > +		if (unlikely(!vc)) {
> > +			pr_warn("%s:failed to allocate memory for the %u vc\n",
> > +					__func__, currcons);
> > +			break;
> > +		}
> 
> At init, this really can not happen.  Have you see it ever happen?

This is maybe too subtle a fact. The "communication" could be done with 
some GFP_WONTFAIL flag, and have the allocator simply pannic() if it 
ever fails.


Nicolas