net/sun3_82586: Avoid reading past buffer in debug output

[ Upstream commit 4bea747f3fbec33c16d369b2f51e55981d7c78d0 ]

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
Cc: Sam Creasey <sammy@sammy.net>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Simon Horman <horms@kernel.org> # build-tested
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20240206161651.work.876-kees@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/i825xx/sun3_82586.c b/drivers/net/ethernet/i825xx/sun3_82586.c
index 4564ee02c95f61308f9d76d456bee43a9adcc9de..83a6114afbf90bad60ab65caa1ff494ac6f10891 100644 (file)
--- a/drivers/net/ethernet/i825xx/sun3_82586.c
+++ b/drivers/net/ethernet/i825xx/sun3_82586.c
@@ -990,7 +990,7 @@ 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);