Re: [PATCH] scsi: check inquiry buffer length to prevent crash

[Paolo Bonzini]

On 4/26/23 15:37, Théo Maillart wrote:
> --- a/hw/scsi/scsi-generic.c
> +++ b/hw/scsi/scsi-generic.c
> @@ -191,7 +191,7 @@ static int scsi_handle_inquiry_reply(SCSIGenericReq *r, 
> SCSIDevice *s, int len)
>       if ((s->type == TYPE_DISK || s->type == TYPE_ZBC) &&
>           (r->req.cmd.buf[1] & 0x01)) {
>           page = r->req.cmd.buf[2];
> -        if (page == 0xb0) {
> +        if (page == 0xb0 && r->buflen >= 12) {
>               uint64_t max_transfer = calculate_max_transfer(s);
>               stl_be_p(&r->buf[8], max_transfer);
>               /* Also take care of the opt xfer len. */
> --

This is not enough because right below there is a store of bytes 12..15.

The best thing to do is to:

1) do the stores in an "uint8_t buf[8]" on the stack, followed by a 
memcpy to r->buf + 8.

2) add "&& r->buflen > 8" to the condition similar to what you've done 
above.

Paolo