Re: [PATCH] RDMA/rxe: fix possible NULL MR dereference

[lizhijian@xxxxxxxxxxx]

NOTE: This is for-rc

on 12/2/2022 10:57 PM, Li Zhijian wrote:
> Daisuke mentioned that:
> If responder get a zero-byte RDMA Read request, qp->resp.mr
> is not set in check_rkey(). The mr is NULL in this case, and a NULL pointer
> dereference occurs as shown below.
>
>   BUG: kernel NULL pointer dereference, address: 0000000000000010
>   #PF: supervisor write access in kernel mode
>   #PF: error_code(0x0002) - not-present page
>   PGD 0 P4D 0
>   Oops: 0002 [#1] PREEMPT SMP PTI
>   CPU: 2 PID: 3622 Comm: python3 Kdump: loaded Not tainted 6.1.0-rc3+ #34
>   Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
>   RIP: 0010:__rxe_put+0xc/0x60 [rdma_rxe]
>   Code: cc cc cc 31 f6 e8 64 36 1b d3 41 b8 01 00 00 00 44 89 c0 c3 cc cc cc cc 41 89 c0 eb c1 90 0f 1f 44 00 00 41 54 b8 ff ff ff ff <f0> 0f c1 47 10 83 f8 01 74 11 45 31 e4 85 c0 7e 20 44 89 e0 41 5c
>   RSP: 0018:ffffb27bc012ce78 EFLAGS: 00010246
>   RAX: 00000000ffffffff RBX: ffff9790857b0580 RCX: 0000000000000000
>   RDX: ffff979080fe145a RSI: 000055560e3e0000 RDI: 0000000000000000
>   RBP: ffff97909c7dd800 R08: 0000000000000001 R09: e7ce43d97f7bed0f
>   R10: ffff97908b29c300 R11: 0000000000000000 R12: 0000000000000000
>   R13: 0000000000000000 R14: ffff97908b29c300 R15: 0000000000000000
>   FS:  00007f276f7bd740(0000) GS:ffff9792b5c80000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 0000000000000010 CR3: 0000000114230002 CR4: 0000000000060ee0
>   Call Trace:
>    <IRQ>
>    read_reply+0xda/0x310 [rdma_rxe]
>    rxe_responder+0x82d/0xe50 [rdma_rxe]
>    do_task+0x84/0x170 [rdma_rxe]
>    tasklet_action_common.constprop.0+0xa7/0x120
>    __do_softirq+0xcb/0x2ac
>    do_softirq+0x63/0x90
>    </IRQ>
>
> Test mr before dereference it to avoid this problem.
>
> Fixes: b5f9a01fae42 ("RDMA/rxe: Fix mr leak in RESPST_ERR_RNR")
> Reported-by: Daisuke Matsuda <matsuda-daisuke@xxxxxxxxxxx>
> Signed-off-by: Li Zhijian <lizhijian@xxxxxxxxxxx>
> ---
> Hope we can catch up with 6.1
> ---
>   drivers/infiniband/sw/rxe/rxe_resp.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
> index 693081e813ec..bbb9665c64ad 100644
> --- a/drivers/infiniband/sw/rxe/rxe_resp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_resp.c
> @@ -807,7 +807,8 @@ static enum resp_states read_reply(struct rxe_qp *qp,
>   	skb = prepare_ack_packet(qp, &ack_pkt, opcode, payload,
>   				 res->cur_psn, AETH_ACK_UNLIMITED);
>   	if (!skb) {
> -		rxe_put(mr);
> +		if (mr)
> +			rxe_put(mr);
>   		return RESPST_ERR_RNR;
>   	}
>