Re: usb: does USBMALLOC_ZERO work correctly?

[Jared McNeill <jmcneill%invisible.ca@localhost>]

Good catch! I've committed a slightly modified version of your patch.

Take care,
Jared


On Thu, 27 May 2021, sc.dying%gmail.com@localhost wrote:

> hi,
>
> sometimes memories allocated by usb_allocmem with USBMALLOC_ZERO
> are not cleared.
> usb_block_allocmem, called from usb_allocmem, returns with valid dmap
> if it has found a block in usb_blk_freelist. In that path memset is not done.
>
>
> --- src/sys/dev/usb/usb_mem.c.orig	2021-01-05 22:12:39.913414469 +0000
> +++ src/sys/dev/usb/usb_mem.c	2021-05-27 01:36:53.189148366 +0000
> @@ -135,6 +135,11 @@ usb_block_allocmem(bus_dma_tag_t tag, si
> 			usb_blk_nfree--;
> 			*dmap = b;
> 			DPRINTFN(6, "free list size=%ju", b->size, 0, 0, 0);
> +			if ((flags & USBMALLOC_ZERO) != 0) {
> +				memset(b->kaddr, 0, b->size);
> +				bus_dmamap_sync(b->tag, b->map, 0, b->size,
> +				    BUS_DMASYNC_PREWRITE);
> +			}
> 			return 0;
> 		}
> 	}