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SubjectRe: [PATCH v2] usb: storage: add error handling for kcalloc
On Mon, Jun 25, 2018 at 11:22:34AM -0400, Alan Stern wrote:
> On Mon, 25 Jun 2018, Greg Kroah-Hartman wrote:
>
> > On Thu, Jun 14, 2018 at 09:29:11PM +0800, Zhouyang Jia wrote:
> > > When kcalloc fails, the lack of error-handling code may
> > > cause unexpected results.
> > >
> > > This patch adds error-handling code after calling kcalloc.
> > >
> > > Signed-off-by: Zhouyang Jia <jiazhouyang09@gmail.com>
> > > Acked-by: Alan Stern <stern@rowland.harvard.edu>
> > > ---
> > > v1->v2:
> > > - Remove pr_warn statement.
> > > ---
> > > drivers/usb/storage/alauda.c | 3 +++
> > > 1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/usb/storage/alauda.c b/drivers/usb/storage/alauda.c
> > > index 900591d..4e17609 100644
> > > --- a/drivers/usb/storage/alauda.c
> > > +++ b/drivers/usb/storage/alauda.c
> > > @@ -437,6 +437,9 @@ static int alauda_init_media(struct us_data *us)
> > > + MEDIA_INFO(us).blockshift + MEDIA_INFO(us).pageshift);
> > > MEDIA_INFO(us).pba_to_lba = kcalloc(num_zones, sizeof(u16*), GFP_NOIO);
> > > MEDIA_INFO(us).lba_to_pba = kcalloc(num_zones, sizeof(u16*), GFP_NOIO);
> > > + if ((MEDIA_INFO(us).pba_to_lba == NULL)
> > > + || (MEDIA_INFO(us).lba_to_pba == NULL))
> > > + return USB_STOR_TRANSPORT_ERROR;
> >
> > You just leaked memory if only one of these succeeded :(
>
> That's not really true. The memory gets deallocated later on in any
> case, when alauda_info_destructor() calls alauda_free_maps() if not
> before.
>
> More troubling is the fact that this routine (i.e, alauda_init_media)
> gets called from only one place, in alauda_check_media, and the caller
> completely ignores the return value! Furthermore, the caller always
> returns USB_STOR_TRANSPORT_FAILED.
>
> So on the whole, I don't think this patch is going to make any
> difference to the driver's operation.

Ok, I'm just going to drop it then.

thanks,

greg k-h

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