Re: [PATCH] net/sun3_82586: Avoid reading past buffer in debug output

[Gustavo A. R. Silva]

On 2/6/24 10:16, Kees Cook wrote:
> Since NUM_XMIT_BUFFS is always 1, building m68k with sun3_defconfig and
> -Warraybounds, this build warning is visible[1]:
>
> drivers/net/ethernet/i825xx/sun3_82586.c: In function 'sun3_82586_timeout':
> drivers/net/ethernet/i825xx/sun3_82586.c:990:122: warning: array subscript 1 is above array bounds of 'volatile struct transmit_cmd_struct *[1]' [-Warray-bounds=]
>    990 |                 printk("%s: command-stats: %04x %04x\n",dev->name,swab16(p->xmit_cmds[0]->cmd_status),swab16(p->xmit_cmds[1]->cmd_status));
>        |                                                                                                               ~~~~~~~~~~~~^~~
> ...
> drivers/net/ethernet/i825xx/sun3_82586.c:156:46: note: while referencing 'xmit_cmds'
>    156 |         volatile struct transmit_cmd_struct *xmit_cmds[NUM_XMIT_BUFFS];
>
> Avoid accessing index 1 since it doesn't exist.
>
> Link: https://github.com/KSPP/linux/issues/325 [1]
> Cc: Sam Creasey <sammy@xxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
> Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
> Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
> Cc: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>

Thanks!
--
Gustavo

> ---
>   drivers/net/ethernet/i825xx/sun3_82586.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/i825xx/sun3_82586.c b/drivers/net/ethernet/i825xx/sun3_82586.c
> index 5e27470c6b1e..f2d4669c81cf 100644
> --- a/drivers/net/ethernet/i825xx/sun3_82586.c
> +++ b/drivers/net/ethernet/i825xx/sun3_82586.c
> @@ -987,7 +987,7 @@ static void sun3_82586_timeout(struct net_device *dev, unsigned int txqueue)
>   	{
>   #ifdef DEBUG
>   		printk("%s: xmitter timed out, try to restart! stat: %02x\n",dev->name,p->scb->cus);
> -		printk("%s: command-stats: %04x %04x\n",dev->name,swab16(p->xmit_cmds[0]->cmd_status),swab16(p->xmit_cmds[1]->cmd_status));
> +		printk("%s: command-stats: %04x\n", dev->name, swab16(p->xmit_cmds[0]->cmd_status));
>   		printk("%s: check, whether you set the right interrupt number!\n",dev->name);
>   #endif
>   		sun3_82586_close(dev);