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[213.113.113.54]) by smtp.gmail.com with ESMTPSA id v198sm2390242lfa.34.2017.10.04.02.10.11 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 04 Oct 2017 02:10:12 -0700 (PDT) From: Linus Walleij To: linux-mmc@vger.kernel.org, Ulf Hansson Cc: Adrian Hunter , Linus Walleij Subject: [PATCH v4] mmc: block: Fix bug when removing RPMB chardev Date: Wed, 4 Oct 2017 11:10:07 +0200 Message-Id: <20171004091007.26729-1-linus.walleij@linaro.org> X-Mailer: git-send-email 2.13.5 Sender: linux-mmc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org I forgot to account for the fact that the device core holds a reference to a device added with device_initialize() that need to be released with a corresponding put_device() to reach a 0 refcount at the end of the lifecycle. This led to a NULL pointer reference when freeing the device when e.g. unbidning the host device in sysfs. Fix this and use the device .release() callback to free the IDA and free:ing the memory used by the RPMB device. Before this patch: /sys/bus/amba/drivers/mmci-pl18x$ echo 80114000.sdi4_per2 > unbind [ 29.797332] mmc3: card 0001 removed [ 29.810791] Unable to handle kernel NULL pointer dereference at virtual address 00000050 [ 29.818878] pgd = de70c000 [ 29.821624] [00000050] *pgd=1e70a831, *pte=00000000, *ppte=00000000 [ 29.827911] Internal error: Oops: 17 [#1] PREEMPT SMP ARM [ 29.833282] Modules linked in: [ 29.836334] CPU: 1 PID: 154 Comm: sh Not tainted 4.14.0-rc3-00039-g83318e309566-dirty #736 [ 29.844604] Hardware name: ST-Ericsson Ux5x0 platform (Device Tree Support) [ 29.851562] task: de572700 task.stack: de742000 [ 29.856079] PC is at kernfs_find_ns+0x8/0x100 [ 29.860443] LR is at kernfs_find_and_get_ns+0x30/0x48 After this patch: /sys/bus/amba/drivers/mmci-pl18x$ echo 80005000.sdi4_per2 > unbind [ 20.623382] mmc3: card 0001 removed Fixes: 0ab0c7c0e65a ("mmc: block: Convert RPMB to a character device") Reported-by: Adrian Hunter Signed-off-by: Linus Walleij --- ChangeLog v3->v4: - Also skip the lock now that we take it inside mmc_blk_get()/ mmc_blk_put() ChangeLog v2->v3: - Fix the block device reference counting: instead of manipulating md->usage directly, call the proper refcounting functions mmc_blk_get() and mmc_blk_put(). ChangeLog v1->v2: - Drop the print from removing the RPMB partition - Refactor the error path of the RPMB to use refcounting - Drop the verbose comment on refcounts --- drivers/mmc/core/block.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-) -- 2.13.5 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Acked-by: Adrian Hunter diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c index c29dbcec7c61..ea80ff4cd7f9 100644 --- a/drivers/mmc/core/block.c +++ b/drivers/mmc/core/block.c @@ -2298,9 +2298,7 @@ static int mmc_rpmb_chrdev_open(struct inode *inode, struct file *filp) get_device(&rpmb->dev); filp->private_data = rpmb; - mutex_lock(&open_lock); - rpmb->md->usage++; - mutex_unlock(&open_lock); + mmc_blk_get(rpmb->md->disk); return nonseekable_open(inode, filp); } @@ -2311,9 +2309,7 @@ static int mmc_rpmb_chrdev_release(struct inode *inode, struct file *filp) struct mmc_rpmb_data, chrdev); put_device(&rpmb->dev); - mutex_lock(&open_lock); - rpmb->md->usage--; - mutex_unlock(&open_lock); + mmc_blk_put(rpmb->md); return 0; } @@ -2329,6 +2325,13 @@ static const struct file_operations mmc_rpmb_fileops = { #endif }; +static void mmc_blk_rpmb_device_release(struct device *dev) +{ + struct mmc_rpmb_data *rpmb = dev_get_drvdata(dev); + + ida_simple_remove(&mmc_rpmb_ida, rpmb->id); + kfree(rpmb); +} static int mmc_blk_alloc_rpmb_part(struct mmc_card *card, struct mmc_blk_data *md, @@ -2347,8 +2350,10 @@ static int mmc_blk_alloc_rpmb_part(struct mmc_card *card, return devidx; rpmb = kzalloc(sizeof(*rpmb), GFP_KERNEL); - if (!rpmb) + if (!rpmb) { + ida_simple_remove(&mmc_rpmb_ida, devidx); return -ENOMEM; + } snprintf(rpmb_name, sizeof(rpmb_name), "mmcblk%u%s", card->host->index, subname ? subname : ""); @@ -2359,6 +2364,7 @@ static int mmc_blk_alloc_rpmb_part(struct mmc_card *card, rpmb->dev.bus = &mmc_rpmb_bus_type; rpmb->dev.devt = MKDEV(MAJOR(mmc_rpmb_devt), rpmb->id); rpmb->dev.parent = &card->dev; + rpmb->dev.release = mmc_blk_rpmb_device_release; device_initialize(&rpmb->dev); dev_set_drvdata(&rpmb->dev, rpmb); rpmb->md = md; @@ -2368,7 +2374,7 @@ static int mmc_blk_alloc_rpmb_part(struct mmc_card *card, ret = cdev_device_add(&rpmb->chrdev, &rpmb->dev); if (ret) { pr_err("%s: could not add character device\n", rpmb_name); - goto out_remove_ida; + goto out_put_device; } list_add(&rpmb->node, &md->rpmbs); @@ -2383,18 +2389,16 @@ static int mmc_blk_alloc_rpmb_part(struct mmc_card *card, return 0; -out_remove_ida: - ida_simple_remove(&mmc_rpmb_ida, rpmb->id); - kfree(rpmb); +out_put_device: + put_device(&rpmb->dev); return ret; } static void mmc_blk_remove_rpmb_part(struct mmc_rpmb_data *rpmb) + { cdev_device_del(&rpmb->chrdev, &rpmb->dev); - device_del(&rpmb->dev); - ida_simple_remove(&mmc_rpmb_ida, rpmb->id); - kfree(rpmb); + put_device(&rpmb->dev); } /* MMC Physical partitions consist of two boot partitions and