[PATCH] RDMA/cma: prevent rdma id destroy during cma_iw_handler

[Leon Romanovsky]

On Sat, Jun 03, 2023 at 09:46:20AM +0900, Shin'ichiro Kawasaki wrote:
> When rdma_destroy_id() and cma_iw_handler() race, struct rdma_id_private
> *id_priv can be destroyed during cma_iw_handler call. This causes "BUG:
> KASAN: slab-use-after-free" at mutex_lock() in cma_iw_handler().
> To prevent the destroy of id_priv, keep its reference count by calling
> cma_id_get() and cma_id_put() at start and end of cma_iw_handler().

Please add relevant kernel panic to commit message.

> 
> Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki at wdc.com>
> Cc: stable at vger.kernel.org

Add Fixes line when you are fixing bug.

> ---
> The BUG KASAN was observed with blktests at test cases nvme/030 or nvme/031,
> using SIW transport [1]. To reproduce it, it is required to repeat the test
> cases from 30 to 50 times on my test system.
> 
> [1] https://lore.kernel.org/linux-block/rsmmxrchy6voi5qhl4irss5sprna3f5owkqtvybxglcv2pnylm@xmrnpfu3tfpe/
> 
>  drivers/infiniband/core/cma.c | 3 +++
>  1 file changed, 3 insertions(+)

The fix looks correct to me.

Thanks