Re: [PATCH v2] RDMA/rxe: Fix double free in rxe_srq_from_init

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

在 2026/1/11 17:54, Jiasheng Jiang 写道:
> In rxe_srq_from_init(), the queue pointer 'q' is assigned to
> 'srq->rq.queue' before copying the SRQ number to user space.
> If copy_to_user() fails, the function calls rxe_queue_cleanup()
> to free the queue, but leaves the now-invalid pointer in
> 'srq->rq.queue'.
> 
> The caller of rxe_srq_from_init() (rxe_create_srq) eventually
> calls rxe_srq_cleanup() upon receiving the error, which triggers
> a second rxe_queue_cleanup() on the same memory, leading to a
> double free.
> 
> The call trace looks like this:
>     kmem_cache_free+0x.../0x...
>     rxe_queue_cleanup+0x1a/0x30 [rdma_rxe]
>     rxe_srq_cleanup+0x42/0x60 [rdma_rxe]
>     rxe_elem_release+0x31/0x70 [rdma_rxe]
>     rxe_create_srq+0x12b/0x1a0 [rdma_rxe]
>     ib_create_srq_user+0x9a/0x150 [ib_core]
> 
> Fix this by moving 'srq->rq.queue = q' after copy_to_user.
> 
> Fixes: aae0484e15f0 ("IB/rxe: avoid srq memory leak")
> Signed-off-by: Jiasheng Jiang <jiashengjiangcool@gmail.com>
> ---
> Changelog:
> 
> v1 -> v2:
> 
> 1. Move both 'srq->rq.queue = q' and 'init->attr.max_wr = srq->rq.max_wr'
> after copy_to_user().
> 2. Add call trace for better understanding of the issue.

Thanks a lot.
Reviewed-by: Zhu Yanjun <yanjun.Zhu@linux.dev>

Zhu Yanjun

> ---
>   drivers/infiniband/sw/rxe/rxe_srq.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/infiniband/sw/rxe/rxe_srq.c b/drivers/infiniband/sw/rxe/rxe_srq.c
> index 2a234f26ac10..c9a7cd38953d 100644
> --- a/drivers/infiniband/sw/rxe/rxe_srq.c
> +++ b/drivers/infiniband/sw/rxe/rxe_srq.c
> @@ -77,9 +77,6 @@ int rxe_srq_from_init(struct rxe_dev *rxe, struct rxe_srq *srq,
>   		goto err_free;
>   	}
>   
> -	srq->rq.queue = q;
> -	init->attr.max_wr = srq->rq.max_wr;
> -
>   	if (uresp) {
>   		if (copy_to_user(&uresp->srq_num, &srq->srq_num,
>   				 sizeof(uresp->srq_num))) {
> @@ -88,6 +85,9 @@ int rxe_srq_from_init(struct rxe_dev *rxe, struct rxe_srq *srq,
>   		}
>   	}
>   
> +	srq->rq.queue = q;
> +	init->attr.max_wr = srq->rq.max_wr;
> +
>   	return 0;
>   
>   err_free: