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mmc: block: ensure error propagation for non-blk

PATCH New Christian Loehle 1 participant 1 message Jun 5, 2023

Subsystems (2)
Stable branch MMC, SD and SDIO
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Christian Loehle

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PATCH 1/1 mmc: block: ensure error propagation for non-blk

commit 003fb0a51162d940f25fc35e70b0996a12c9e08a upstream.

Requests to the mmc layer usually come through a block device IO. The exceptions are the ioctl interface, RPMB chardev ioctl and debugfs, which issue their own blk_mq requests through blk_execute_rq and do not query the BLK_STS error but the mmcblk-internal drv_op_result. This patch ensures that drv_op_result defaults to an error and has to be overwritten by the operation to be considered successful.

The behavior leads to a bug where the request never propagates the error, e.g. by directly erroring out at mmc_blk_mq_issue_rq if mmc_blk_part_switch fails. The ioctl caller of the rpmb chardev then can never see an error (BLK_STS_IOERR, but drv_op_result is unchanged) and thus may assume that their call executed successfully when it did not.

While always checking the blk_execute_rq return value would be advised, let's eliminate the error by always setting drv_op_result as -EIO to be overwritten on success (or other error)

Fixes 614f0388f580 ("mmc: block: move single ioctl() commands to block requests")
Signed-off-by Christian Loehle <[email protected]>
---
 drivers/mmc/core/block.c | 5 +++++
 1 file changed, 5 insertions(+)
drivers/mmc/core/block.c +5 -0
index ed034b93cb25..0b72096f10e6 100644
@@ -265,6 +265,7 @@ static ssize_t power_ro_lock_store(struct device *dev,
 		goto out_put;
 	}
 	req_to_mmc_queue_req(req)->drv_op = MMC_DRV_OP_BOOT_WP;
+	req_to_mmc_queue_req(req)->drv_op_result = -EIO;
 	blk_execute_rq(NULL, req, 0);
 	ret = req_to_mmc_queue_req(req)->drv_op_result;
 	blk_put_request(req);

@@ -656,6 +657,7 @@ static int mmc_blk_ioctl_cmd(struct mmc_blk_data *md,
 	idatas[0] = idata;
 	req_to_mmc_queue_req(req)->drv_op =
 		rpmb ? MMC_DRV_OP_IOCTL_RPMB : MMC_DRV_OP_IOCTL;
+	req_to_mmc_queue_req(req)->drv_op_result = -EIO;
 	req_to_mmc_queue_req(req)->drv_op_data = idatas;
 	req_to_mmc_queue_req(req)->ioc_count = 1;
 	blk_execute_rq(NULL, req, 0);

@@ -725,6 +727,7 @@ static int mmc_blk_ioctl_multi_cmd(struct mmc_blk_data *md,
 	}
 	req_to_mmc_queue_req(req)->drv_op =
 		rpmb ? MMC_DRV_OP_IOCTL_RPMB : MMC_DRV_OP_IOCTL;
+	req_to_mmc_queue_req(req)->drv_op_result = -EIO;
 	req_to_mmc_queue_req(req)->drv_op_data = idata;
 	req_to_mmc_queue_req(req)->ioc_count = num_of_cmds;
 	blk_execute_rq(NULL, req, 0);

@@ -2784,6 +2787,7 @@ static int mmc_dbg_card_status_get(void *data, u64 *val)
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 	req_to_mmc_queue_req(req)->drv_op = MMC_DRV_OP_GET_CARD_STATUS;
+	req_to_mmc_queue_req(req)->drv_op_result = -EIO;
 	blk_execute_rq(NULL, req, 0);
 	ret = req_to_mmc_queue_req(req)->drv_op_result;
 	if (ret >= 0) {

@@ -2822,6 +2826,7 @@ static int mmc_ext_csd_open(struct inode *inode, struct file *filp)
 		goto out_free;
 	}
 	req_to_mmc_queue_req(req)->drv_op = MMC_DRV_OP_GET_EXT_CSD;
+	req_to_mmc_queue_req(req)->drv_op_result = -EIO;
 	req_to_mmc_queue_req(req)->drv_op_data = &ext_csd;
 	blk_execute_rq(NULL, req, 0);
 	err = req_to_mmc_queue_req(req)->drv_op_result;

--
2.37.3