Patch "mmc: block: fix updating ext_csd caches on ioctl call" has been added to the 4.15-stable tree

This is a note to let you know that I've just added the patch titled

mmc: block: fix updating ext_csd caches on ioctl call

to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mmc-block-fix-updating-ext_csd-caches-on-ioctl-call.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Bastian Stender <[email protected]>
Date: Thu, 8 Mar 2018 15:08:11 +0100
Subject: mmc: block: fix updating ext_csd caches on ioctl call

From: Bastian Stender <[email protected]>

commit e74ef2194b41ba5e511fab29fe5ff00e72d2f42a upstream.

PARTITION_CONFIG is cached in mmc_card->ext_csd.part_config and the currently active partition in mmc_blk_data->part_curr. These caches do not always reflect changes if the ioctl call modifies the PARTITION_CONFIG registers, e.g. by changing BOOT_PARTITION_ENABLE.

Write the PARTITION_CONFIG value extracted from the ioctl call to the cache and update the currently active partition accordingly. This ensures that the user space cannot change the values behind the kernel's back. The next call to mmc_blk_part_switch() will operate on the data set by the ioctl and reflect the changes appropriately.

---
 drivers/mmc/core/block.c |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

@@ -66,6 +66,7 @@ MODULE_ALIAS("mmc:block");
 #define MMC_BLK_TIMEOUT_MS  (10 * 60 * 1000)        /* 10 minute timeout */
 #define MMC_SANITIZE_REQ_TIMEOUT 240000
 #define MMC_EXTRACT_INDEX_FROM_ARG(x) ((x & 0x00FF0000) >> 16)
+#define MMC_EXTRACT_VALUE_FROM_ARG(x) ((x & 0x0000FF00) >> 8)
 
 #define mmc_req_rel_wr(req)	((req->cmd_flags & REQ_FUA) && \
 				  (rq_data_dir(req) == WRITE))

@@ -580,6 +581,24 @@ static int __mmc_blk_ioctl_cmd(struct mm
 	}
 
 	/*
+	 * Make sure the cache of the PARTITION_CONFIG register and
+	 * PARTITION_ACCESS bits is updated in case the ioctl ext_csd write
+	 * changed it successfully.
+	 */
+	if ((MMC_EXTRACT_INDEX_FROM_ARG(cmd.arg) == EXT_CSD_PART_CONFIG) &&
+	    (cmd.opcode == MMC_SWITCH)) {
+		struct mmc_blk_data *main_md = dev_get_drvdata(&card->dev);
+		u8 value = MMC_EXTRACT_VALUE_FROM_ARG(cmd.arg);
+
+		/*
+		 * Update cache so the next mmc_blk_part_switch call operates
+		 * on up-to-date data.
+		 */
+		card->ext_csd.part_config = value;
+		main_md->part_curr = value & EXT_CSD_PART_CONFIG_ACC_MASK;
+	}
+
+	/*
 	 * According to the SD specs, some commands require a delay after
 	 * issuing the command.
 	 */

Patches currently in stable-queue which might be from [email protected] are

queue-4.15/mmc-block-fix-updating-ext_csd-caches-on-ioctl-call.patch