Re: [PATCH] hw/usb/hcd-dwc2: Handle invalid address access in read and write functions

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Cc'ing Paul.

On 18/6/24 15:56, Zheyu Ma wrote:
> This commit modifies the dwc2_hsotg_read() and dwc2_hsotg_write() functions
> to handle invalid address access gracefully. Instead of using
> g_assert_not_reached(), which causes the program to abort, the functions
> now log an error message and return a default value for reads or do
> nothing for writes.
> 
> This change prevents the program from aborting and provides clear log
> messages indicating when an invalid memory address is accessed.
> 
> Reproducer:
> cat << EOF | qemu-system-aarch64 -display none \
> -machine accel=qtest, -m 512M -machine raspi2b -m 1G -nodefaults \
> -usb -drive file=null-co://,if=none,format=raw,id=disk0 -device \
> usb-storage,port=1,drive=disk0 -qtest stdio
> readl 0x3f980dfb
> EOF
> 
> Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
> ---
>   hw/usb/hcd-dwc2.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/usb/hcd-dwc2.c b/hw/usb/hcd-dwc2.c
> index 8cac9c0a06..b4f0652c7d 100644
> --- a/hw/usb/hcd-dwc2.c
> +++ b/hw/usb/hcd-dwc2.c
> @@ -1128,7 +1128,10 @@ static uint64_t dwc2_hsotg_read(void *ptr, hwaddr addr, unsigned size)
>           val = dwc2_pcgreg_read(ptr, addr, (addr - HSOTG_REG(0xe00)) >> 2, size);
>           break;
>       default:
> -        g_assert_not_reached();
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%"HWADDR_PRIx"\n",
> +                      __func__, addr);
> +        val = 0;
> +        break;
>       }
>   
>       return val;
> @@ -1160,7 +1163,9 @@ static void dwc2_hsotg_write(void *ptr, hwaddr addr, uint64_t val,
>           dwc2_pcgreg_write(ptr, addr, (addr - HSOTG_REG(0xe00)) >> 2, val, size);
>           break;
>       default:
> -        g_assert_not_reached();
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%"HWADDR_PRIx"\n",
> +                      __func__, addr);
> +        break;
>       }
>   }
>