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

[Leon Romanovsky <leon@kernel.org>]

On Tue, Oct 21, 2025 at 10:20:26AM +0800, Yi Liu 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
> 
> Fix by 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.
> 
> Reported-by: Liu Yi <asatsuyu.liu@gmail.com>
> Link: https://paste.ubuntu.com/p/Zhj65q6gr9/
> Fixes: 8700e3e7c485 ("Soft RoCE driver")
> Tested-by: Zhu Yanjun <yanjun.zhu@linux.dev>
> Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
> ---
> drivers/infiniband/sw/rxe/rxe_srq.c | 2 --
> 1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/infiniband/sw/rxe/rxe_srq.c
> b/drivers/infiniband/sw/rxe/rxe_srq.c
> index 3661cb627d28..2764dc00e2f3 100644
> --- a/drivers/infiniband/sw/rxe/rxe_srq.c
> +++ b/drivers/infiniband/sw/rxe/rxe_srq.c
> @@ -182,8 +182,6 @@ int rxe_srq_from_attr(struct rxe_dev *rxe, struct
> rxe_srq *srq,
> return 0;
> 
> err_free:
> - rxe_queue_cleanup(q);
> - srq->rq.queue = NULL;
> return err;
> }

This patch is badly formatted and doesn't apply.

Applying: RDMA/rxe: fix null deref on srq->rq.queue after resize failure
Patch failed at 0001 RDMA/rxe: fix null deref on srq->rq.queue after resize failure
error: git diff header lacks filename information when removing 1 leading pathname component (line 6)
hint: Use 'git am --show-current-patch=diff' to see the failed patch
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> 
> --
> 2.34.1