Re: [Qemu-devel] [PATCH] Allow to register a callback with fw_cfg_add_callback()

[Gleb Natapov <gleb@redhat.com>]

On Thu, Dec 11, 2008 at 04:09:28PM +0100, Laurent Vivier wrote:
> fw_cfg_add_callback() checks if key has FW_CFG_WRITE_CHANNEL bit set
> after masking the key with FW_CFG_ENTRY_MASK.
> 
> But as FW_CFG_ENTRY_MASK is ~(FW_CFG_WRITE_CHANNEL | FW_CFG_ARCH_LOCAL),
> the bit is never set and function exits.
> 
> This patch corrects this by checking the bit before masking the value.
> 
> Signed-by-off: Laurent Vivier <Laurent.Vivier@bull.net>
Acked-by: Gleb Natapov <gleb@redhat.com>

> ---
>  hw/fw_cfg.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> Index: qemu/hw/fw_cfg.c
> ===================================================================
> --- qemu.orig/hw/fw_cfg.c	2008-12-11 15:55:15.000000000 +0100
> +++ qemu/hw/fw_cfg.c	2008-12-11 15:55:41.000000000 +0100
> @@ -240,10 +240,12 @@ int fw_cfg_add_callback(void *opaque, ui
>      FWCfgState *s = opaque;
>      int arch = !!(key & FW_CFG_ARCH_LOCAL);
>  
> +    if (!(key & FW_CFG_WRITE_CHANNEL))
> +        return 0;
> +
>      key &= FW_CFG_ENTRY_MASK;
>  
> -    if (key >= FW_CFG_MAX_ENTRY || !(key & FW_CFG_WRITE_CHANNEL)
> -        || len > 65535)
> +    if (key >= FW_CFG_MAX_ENTRY || len > 65535)
>          return 0;
>  
>      s->entries[arch][key].data = data;
> 

--
			Gleb.