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

[Leon Romanovsky <leon@kernel.org>]

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.

Thanks