Re: [PATCH] RDMA/rxe: Fix null pointer dereference in ODP MR check

[Zhu Yanjun <yanjun.zhu@linux.dev>]

在 2025/4/2 5:26, Li Zhijian 写道:
> The blktests/rnbd reported a null pointer dereference as following.
> Similar to the mxl5, introduce a is_odp_mr() to check if the odp
> is enabled in this mr.
> 
> Workqueue: rxe_wq do_work [rdma_rxe]
> RIP: 0010:rxe_mr_copy+0x57/0x210 [rdma_rxe]
> Code: 7c 04 48 89 f3 48 89 d5 41 89 cf 45 89 c4 0f 84 dc 00 00 00 89 ca e8 f8 f8 ff ff 85 c0 0f 85 75 01 00 00 49 8b 86 f0 00 00 00 <f6> 40 28 02 0f 85 98 01 00 00 41 8b 46 78 41 8b 8e 10 01 00 00 8d
> RSP: 0018:ffffa0aac02cfcf8 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: ffff9079cd440024 RCX: 0000000000000000
> RDX: 000000000000003c RSI: ffff9079cd440060 RDI: ffff9079cd665600
> RBP: ffff9079c0e5e45a R08: 0000000000000000 R09: 0000000000000000
> R10: 000000003c000000 R11: 0000000000225510 R12: 0000000000000000
> R13: 0000000000000000 R14: ffff9079cd665600 R15: 000000000000003c
> FS:  0000000000000000(0000) GS:ffff907ccfa80000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000028 CR3: 0000000119498001 CR4: 00000000001726f0
> Call Trace:
>   <TASK>
>   ? __die_body+0x1e/0x60
>   ? page_fault_oops+0x14f/0x4c0
>   ? rxe_mr_copy+0x57/0x210 [rdma_rxe]
>   ? search_bpf_extables+0x5f/0x80
>   ? exc_page_fault+0x7e/0x180
>   ? asm_exc_page_fault+0x26/0x30
>   ? rxe_mr_copy+0x57/0x210 [rdma_rxe]
>   ? rxe_mr_copy+0x48/0x210 [rdma_rxe]
>   ? rxe_pool_get_index+0x50/0x90 [rdma_rxe]
>   rxe_receiver+0x1d98/0x2530 [rdma_rxe]
>   ? psi_task_switch+0x1ff/0x250
>   ? finish_task_switch+0x92/0x2d0
>   ? __schedule+0xbdf/0x17c0
>   do_task+0x65/0x1e0 [rdma_rxe]
>   process_scheduled_works+0xaa/0x3f0
>   worker_thread+0x117/0x240
> 
> Fixes: d03fb5c6599e ("RDMA/rxe: Allow registering MRs for On-Demand Paging")
> Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
> ---
>   drivers/infiniband/sw/rxe/rxe_loc.h  | 6 ++++++
>   drivers/infiniband/sw/rxe/rxe_mr.c   | 4 ++--
>   drivers/infiniband/sw/rxe/rxe_resp.c | 4 ++--
>   3 files changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h
> index feb386d98d1d..0bc3fbb6554f 100644
> --- a/drivers/infiniband/sw/rxe/rxe_loc.h
> +++ b/drivers/infiniband/sw/rxe/rxe_loc.h
> @@ -140,6 +140,12 @@ static inline int qp_mtu(struct rxe_qp *qp)
>   		return IB_MTU_4096;
>   }
>   
> +static inline bool is_odp_mr(struct rxe_mr *mr)

Previously I once discussed with Bob Pearson about the function names.
Perhaps it is better to rename is_odp_mr to rxe_is_odp_mr?

Since sometimes we debug in rdma, with a lot of functions with the same 
name, it is difficult to recognize the modules that this function 
belongs to.

Thus, in rxe module, it is better to add rxe_ prefix to the function 
name. But anyway, this commit is fine.

Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>

Zhu Yanjun

> +{
> +	return IS_ENABLED(CONFIG_INFINIBAND_ON_DEMAND_PAGING) && mr->umem &&
> +	       mr->umem->is_odp;
> +}
> +
>   void free_rd_atomic_resource(struct resp_res *res);
>   
>   static inline void rxe_advance_resp_resource(struct rxe_qp *qp)
> diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
> index 868d2f0b74e9..432d864c3ce9 100644
> --- a/drivers/infiniband/sw/rxe/rxe_mr.c
> +++ b/drivers/infiniband/sw/rxe/rxe_mr.c
> @@ -323,7 +323,7 @@ int rxe_mr_copy(struct rxe_mr *mr, u64 iova, void *addr,
>   		return err;
>   	}
>   
> -	if (mr->umem->is_odp)
> +	if (is_odp_mr(mr))
>   		return rxe_odp_mr_copy(mr, iova, addr, length, dir);
>   	else
>   		return rxe_mr_copy_xarray(mr, iova, addr, length, dir);
> @@ -536,7 +536,7 @@ int rxe_mr_do_atomic_write(struct rxe_mr *mr, u64 iova, u64 value)
>   	u64 *va;
>   
>   	/* ODP is not supported right now. WIP. */
> -	if (mr->umem->is_odp)
> +	if (is_odp_mr(mr))
>   		return RESPST_ERR_UNSUPPORTED_OPCODE;
>   
>   	/* See IBA oA19-28 */
> diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
> index 54ba9ee1acc5..5d9174e408db 100644
> --- a/drivers/infiniband/sw/rxe/rxe_resp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_resp.c
> @@ -650,7 +650,7 @@ static enum resp_states process_flush(struct rxe_qp *qp,
>   	struct resp_res *res = qp->resp.res;
>   
>   	/* ODP is not supported right now. WIP. */
> -	if (mr->umem->is_odp)
> +	if (is_odp_mr(mr))
>   		return RESPST_ERR_UNSUPPORTED_OPCODE;
>   
>   	/* oA19-14, oA19-15 */
> @@ -706,7 +706,7 @@ static enum resp_states atomic_reply(struct rxe_qp *qp,
>   	if (!res->replay) {
>   		u64 iova = qp->resp.va + qp->resp.offset;
>   
> -		if (mr->umem->is_odp)
> +		if (is_odp_mr(mr))
>   			err = rxe_odp_atomic_op(mr, iova, pkt->opcode,
>   						atmeth_comp(pkt),
>   						atmeth_swap_add(pkt),