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

[Simon Horman]

On Tue, Feb 06, 2024 at 08:16:54AM -0800, 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: Simon Horman <horms@xxxxxxxxxx>
Tested-by: Simon Horman <horms@xxxxxxxxxx> # build-tested

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