From: Peter Wang peter.wang@mediatek.com

When ufshcd_clear_cmd racing with complete ISR, the completed tag of request's mq_hctx pointer will set NULL by ISR. And ufshcd_clear_cmd call ufshcd_mcq_req_to_hwq will get NULL pointer KE. Return success when request is completed by ISR beacuse sq dosen't need cleanup.

The racing flow is:

Thread A ufshcd_err_handler step 1 ufshcd_try_to_abort_task ufshcd_cmd_inflight(true) step 3 ufshcd_clear_cmd ... ufshcd_mcq_req_to_hwq blk_mq_unique_tag rq->mq_hctx->queue_num step 5

Thread B ufs_mtk_mcq_intr(cq complete ISR) step 2 scsi_done ... __blk_mq_free_request rq->mq_hctx = NULL; step 4

Below is KE back trace:

ufshcd_try_to_abort_task: cmd pending in the device. tag = 6 Unable to handle kernel NULL pointer dereference at virtual address 0000000000000194 pc : [0xffffffd589679bf8] blk_mq_unique_tag+0x8/0x14 lr : [0xffffffd5862f95b4] ufshcd_mcq_sq_cleanup+0x6c/0x1cc [ufs_mediatek_mod_ise] Workqueue: ufs_eh_wq_0 ufshcd_err_handler [ufs_mediatek_mod_ise] Call trace: dump_backtrace+0xf8/0x148 show_stack+0x18/0x24 dump_stack_lvl+0x60/0x7c dump_stack+0x18/0x3c mrdump_common_die+0x24c/0x398 [mrdump] ipanic_die+0x20/0x34 [mrdump] notify_die+0x80/0xd8 die+0x94/0x2b8 __do_kernel_fault+0x264/0x298 do_page_fault+0xa4/0x4b8 do_translation_fault+0x38/0x54 do_mem_abort+0x58/0x118 el1_abort+0x3c/0x5c el1h_64_sync_handler+0x54/0x90 el1h_64_sync+0x68/0x6c blk_mq_unique_tag+0x8/0x14 ufshcd_clear_cmd+0x34/0x118 [ufs_mediatek_mod_ise] ufshcd_try_to_abort_task+0x2c8/0x5b4 [ufs_mediatek_mod_ise] ufshcd_err_handler+0xa7c/0xfa8 [ufs_mediatek_mod_ise] process_one_work+0x208/0x4fc worker_thread+0x228/0x438 kthread+0x104/0x1d4 ret_from_fork+0x10/0x20

Fixes: 8d7290348992 ("scsi: ufs: mcq: Add supporting functions for MCQ abort") Cc: stable@vger.kernel.org 6.6.x Suggested-by: Bart Van Assche bvanassche@acm.org Signed-off-by: Peter Wang peter.wang@mediatek.com --- drivers/ufs/core/ufs-mcq.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/ufs/core/ufs-mcq.c b/drivers/ufs/core/ufs-mcq.c index 8944548c30fa..c532416aec22 100644 --- a/drivers/ufs/core/ufs-mcq.c +++ b/drivers/ufs/core/ufs-mcq.c @@ -105,16 +105,15 @@ EXPORT_SYMBOL_GPL(ufshcd_mcq_config_mac); * @hba: per adapter instance * @req: pointer to the request to be issued * - * Return: the hardware queue instance on which the request would - * be queued. + * Return: the hardware queue instance on which the request will be or has + * been queued. %NULL if the request has already been freed. */ struct ufs_hw_queue *ufshcd_mcq_req_to_hwq(struct ufs_hba *hba, struct request *req) { - u32 utag = blk_mq_unique_tag(req); - u32 hwq = blk_mq_unique_tag_to_hwq(utag); + struct blk_mq_hw_ctx *hctx = READ_ONCE(req->mq_hctx);

- return &hba->uhq[hwq]; + return hctx ? &hba->uhq[hctx->queue_num] : NULL; }

/** @@ -515,6 +514,8 @@ int ufshcd_mcq_sq_cleanup(struct ufs_hba *hba, int task_tag) if (!cmd) return -EINVAL; hwq = ufshcd_mcq_req_to_hwq(hba, scsi_cmd_to_rq(cmd)); + if (!hwq) + return 0; } else { hwq = hba->dev_cmd_queue; }