Re: [PATCH 1/1] RDMA/rxe: Fix null deref on srq->rq.queue after resize failure

["yanjun.zhu" <yanjun.zhu@linux.dev>]

On 10/27/25 1:04 PM, Leon Romanovsky wrote:
> On Mon, Oct 27, 2025 at 10:43:06AM -0700, Zhu Yanjun wrote:
>> A NULL pointer dereference can occur in rxe_srq_chk_attr() when
>> ibv_modify_srq() is invoked twice in succession under certain error
>> conditions. The first call may fail in rxe_queue_resize(), which leads
>> rxe_srq_from_attr() to set srq->rq.queue = NULL. The second call then
>> triggers a crash (null deref) when accessing
>> srq->rq.queue->buf->index_mask.
>>
>> Call Trace:
>> <TASK>
>> rxe_modify_srq+0x170/0x480 [rdma_rxe]
>> ? __pfx_rxe_modify_srq+0x10/0x10 [rdma_rxe]
>> ? uverbs_try_lock_object+0x4f/0xa0 [ib_uverbs]
>> ? rdma_lookup_get_uobject+0x1f0/0x380 [ib_uverbs]
>> ib_uverbs_modify_srq+0x204/0x290 [ib_uverbs]
>> ? __pfx_ib_uverbs_modify_srq+0x10/0x10 [ib_uverbs]
>> ? tryinc_node_nr_active+0xe6/0x150
>> ? uverbs_fill_udata+0xed/0x4f0 [ib_uverbs]
>> ib_uverbs_handler_UVERBS_METHOD_INVOKE_WRITE+0x2c0/0x470 [ib_uverbs]
>> ? __pfx_ib_uverbs_handler_UVERBS_METHOD_INVOKE_WRITE+0x10/0x10 [ib_uverbs]
>> ? uverbs_fill_udata+0xed/0x4f0 [ib_uverbs]
>> ib_uverbs_run_method+0x55a/0x6e0 [ib_uverbs]
>> ? __pfx_ib_uverbs_handler_UVERBS_METHOD_INVOKE_WRITE+0x10/0x10 [ib_uverbs]
>> ib_uverbs_cmd_verbs+0x54d/0x800 [ib_uverbs]
>> ? __pfx_ib_uverbs_cmd_verbs+0x10/0x10 [ib_uverbs]
>> ? __pfx___raw_spin_lock_irqsave+0x10/0x10
>> ? __pfx_do_vfs_ioctl+0x10/0x10
>> ? ioctl_has_perm.constprop.0.isra.0+0x2c7/0x4c0
>> ? __pfx_ioctl_has_perm.constprop.0.isra.0+0x10/0x10
>> ib_uverbs_ioctl+0x13e/0x220 [ib_uverbs]
>> ? __pfx_ib_uverbs_ioctl+0x10/0x10 [ib_uverbs]
>> __x64_sys_ioctl+0x138/0x1c0
>> do_syscall_64+0x82/0x250
>> ? fdget_pos+0x58/0x4c0
>> ? ksys_write+0xf3/0x1c0
>> ? __pfx_ksys_write+0x10/0x10
>> ? do_syscall_64+0xc8/0x250
>> ? __pfx_vm_mmap_pgoff+0x10/0x10
>> ? fget+0x173/0x230
>> ? fput+0x2a/0x80
>> ? ksys_mmap_pgoff+0x224/0x4c0
>> ? do_syscall_64+0xc8/0x250
>> ? do_user_addr_fault+0x37b/0xfe0
>> ? clear_bhb_loop+0x50/0xa0
>> ? clear_bhb_loop+0x50/0xa0
>> ? clear_bhb_loop+0x50/0xa0
>> entry_SYSCALL_64_after_hwframe+0x76/0x7e
>>
>> Root cause:
>>     The queue is released when the first failure of rxe_cq_resize_queue.
>> Thus, when rxe_cq_resize_queue is called again, the above call trace
>> will occur.
>>
>> Fix:
>> Aligning the error handling path in rxe_srq_from_attr() with
>> rxe_cq_resize_queue(), which also uses rxe_queue_resize(): do not
>> nullify the queue when resize fails.
> 
> Did these two paragraphs come from AI? They don't add any new
> information, let's remove them.
> 
>>
>> Reported-by: Liu Yi <asatsuyu.liu@gmail.com>
>> Closes: https://paste.ubuntu.com/p/Zhj65q6gr9/
> 
> Link in "Closes" tag should point to report and not to some random
> place.
> 
>> Fixes: 8700e3e7c485 ("Soft RoCE driver")
>> Tested-by: Liu Yi <asatsuyu.liu@gmail.com>
>> Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
>> ---
>>   drivers/infiniband/sw/rxe/rxe_srq.c | 7 +------
>>   1 file changed, 1 insertion(+), 6 deletions(-)
> 
> It is second version of previously sent patch. Please add changelog.

OK. I will send the 3rd patch.

Yanjun.Zhu
> 
> Thanks