Re: [PATCH v2 1/1] RDMA/cma: Fix WARNING in res_to_rt

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

在 2026/8/10 15:01, Zhu Yanjun 写道:
> syzbot reported a WARN_ON(!res->dev) in res_to_rt() triggered via
> addr_handler() during asynchronous address resolution:
> 
> "
> WARNING: drivers/infiniband/core/restrack.c:138 at res_to_rt+0x1c4/0x230
> CPU#1: kworker/u8:4/59
> Modules linked in:
> CPU: 1 UID: 0 PID: 59 Comm: kworker/u8:4 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: Google Compute Engine, BIOS Google 07/24/2026
> Workqueue: ib_addr process_one_req
> RIP: 0010:res_to_rt+0x1c4/0x230 drivers/infiniband/core/restrack.c:138
> RSP: 0018:ffffc9000201f850 EFLAGS: 00010293
> RAX: ffffffff88d00ce5 RBX: ffff88807f0fd4f8 RCX: ffff88801e6e0000
> RDX: 0000000000000000 RSI: ffffffff8fd996f0 RDI: 0000000000000003
> RBP: 0000000000000000 R08: ffff88801e6e0000 R09: 000000000000000a
> R10: 0000000000000009 R11: 0000000000000000 R12: dffffc0000000000
> R13: 1ffff1100fe1fa9f R14: 0000000000000000 R15: 0000000000000003
> FS:  0000000000000000(0000) GS:ffff888125012000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00001d559c3d2000 CR3: 0000000077c4c000 CR4: 00000000003526f0
> Call Trace:
>   <TASK>
>   rdma_restrack_add+0x5a/0x8a0 drivers/infiniband/core/restrack.c:236
>   addr_handler+0x41a/0x5a0 drivers/infiniband/core/cma.c:3534
>   process_one_req+0x2eb/0x540 drivers/infiniband/core/addr.c:624
>   process_one_work kernel/workqueue.c:3375 [inline]
>   process_scheduled_works+0xc4e/0x1630 kernel/workqueue.c:3458
>   worker_thread+0xa47/0xfb0 kernel/workqueue.c:3539
>   kthread+0x388/0x470 kernel/kthread.c:436
>   ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>   </TASK>
> "
> 
> In addr_handler(), cma_acquire_dev_by_src_ip() is called to populate
> id_priv->cma_dev and bind the associated ib_device to id_priv->id.device.
> If cma_acquire_dev_by_src_ip() returns an error (non-zero status), the ID
> remains unassociated with any RDMA device.
> 
> Previously, rdma_restrack_add(&id_priv->res) was invoked unconditionally
> even when cma_acquire_dev_by_src_ip() failed, passing a resource with a
> NULL dev pointer and triggering the WARN_ON assertion in res_to_rt().
> 
> Fix this by only adding the resource to restrack when acquiring the device
> succeeds.
> 
> Reported-by: syzbot+72eddfbadda3e3928e72@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=72eddfbadda3e3928e72
> Tested-by: syzbot+72eddfbadda3e3928e72@syzkaller.appspotmail.com
> Fixes: cb5cd0ea4eb3 ("RDMA/core: Add CM to restrack after successful attachment to a device")
> 
> Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
> ---
> V1 -> V2: Follow Jason's advice to use if/else to handle this problem.

Thanks, Jason.
I have sent this commit to syzbot. From the reply, this commit can also 
fix the problem in the commit log.

Zhu Yanjun

> ---
>   drivers/infiniband/core/cma.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
> index cc24fddf9aaa..73170b15fc3d 100644
> --- a/drivers/infiniband/core/cma.c
> +++ b/drivers/infiniband/core/cma.c
> @@ -3528,10 +3528,12 @@ static void addr_handler(int status, struct sockaddr *src_addr,
>   	memcpy(addr, src_addr, rdma_addr_size(src_addr));
>   	if (!status && !id_priv->cma_dev) {
>   		status = cma_acquire_dev_by_src_ip(id_priv);
> -		if (status)
> +		if (status) {
>   			pr_debug_ratelimited("RDMA CM: ADDR_ERROR: failed to acquire device. status %d\n",
>   					     status);
> -		rdma_restrack_add(&id_priv->res);
> +		} else {
> +			rdma_restrack_add(&id_priv->res);
> +		}
>   	} else if (status) {
>   		pr_debug_ratelimited("RDMA CM: ADDR_ERROR: failed to resolve IP. status %d\n", status);
>   	}