warn in ncsi netlink code

Joel Stanley
2022-11-17T04:35:36Z

next-20221114 running on an ast2600 system produced this:

[ 44.627332] ------------[ cut here ]------------
[ 44.632657] WARNING: CPU: 0 PID: 508 at net/ncsi/ncsi-cmd.c:231
ncsi_cmd_handler_oem+0xbc/0xd0
[ 44.642387] memcpy: detected field-spanning write (size 7) of
single field "&cmd->mfr_id" at net/ncsi/ncsi-cmd.c:231 (size 4)
[ 44.655131] CPU: 0 PID: 508 Comm: ncsi-netlink Not tainted
6.1.0-rc5-14066-gefbdad8553d8 #17
[ 44.664577] Hardware name: Generic DT based system
[ 44.664599] unwind_backtrace from show_stack+0x18/0x1c
[ 44.675801] show_stack from dump_stack_lvl+0x40/0x4c
[ 44.681458] dump_stack_lvl from __warn+0xb8/0x12c
[ 44.686814] __warn from warn_slowpath_fmt+0x9c/0xd8
[ 44.692370] warn_slowpath_fmt from ncsi_cmd_handler_oem+0xbc/0xd0
[ 44.699285] ncsi_cmd_handler_oem from ncsi_xmit_cmd+0x160/0x29c
[ 44.706002] ncsi_xmit_cmd from ncsi_send_cmd_nl+0x13c/0x1dc
[ 44.712337] ncsi_send_cmd_nl from genl_rcv_msg+0x1d0/0x440
[ 44.718579] genl_rcv_msg from netlink_rcv_skb+0xc0/0x120
[ 44.724623] netlink_rcv_skb from genl_rcv+0x28/0x3c
[ 44.730182] genl_rcv from netlink_unicast+0x208/0x370
[ 44.735934] netlink_unicast from netlink_sendmsg+0x1e4/0x450
[ 44.742365] netlink_sendmsg from ____sys_sendmsg+0x23c/0x2b8
[ 44.748799] ____sys_sendmsg from ___sys_sendmsg+0x9c/0xd0
[ 44.754941] ___sys_sendmsg from sys_sendmsg+0x78/0xbc
[ 44.760695] sys_sendmsg from ret_fast_syscall+0x0/0x54
[ 44.766544] Exception stack(0xb57b1fa8 to 0xb57b1ff0)
[ 44.772191] 1fa0: 0244f330 0244f1e0 00000003
7ee36a60 00000000 00000000
[ 44.781328] 1fc0: 0244f330 0244f1e0 76f35c60 00000128 76f91550
0244f387 0244f387 00498e7c
[ 44.790462] 1fe0: 76f35d34 7ee36a10 76f1b510 76bba140
[ 44.796186] ---[ end trace 0000000000000000 ]---

The relevant code:

static int ncsi_cmd_handler_oem(struct sk_buff *skb,
struct ncsi_cmd_arg *nca)
{
struct ncsi_cmd_oem_pkt *cmd;
unsigned int len;
int payload;
/* NC-SI spec DSP_0222_1.2.0, section 8.2.2.2
* requires payload to be padded with 0 to
* 32-bit boundary before the checksum field.
* Ensure the padding bytes are accounted for in
* skb allocation
*/

payload = ALIGN(nca->payload, 4);
len = sizeof(struct ncsi_cmd_pkt_hdr) + 4;
len += max(payload, padding_bytes);

cmd = skb_put_zero(skb, len);
memcpy(&cmd->mfr_id, nca->data, nca->payload);
ncsi_cmd_build_header(&cmd->cmd.common, nca);

return 0;
}

I think it's copying the command payload to the command packet,
starting at the offset of mfr_id:

struct ncsi_cmd_oem_pkt {
struct ncsi_cmd_pkt_hdr cmd; /* Command header */
__be32 mfr_id; /* Manufacture ID */
unsigned char data[]; /* OEM Payload Data */
};

But I'm not too sure.

Cheers,

Joel