From: Linus Walleij linus.walleij@linaro.org
commit 1c87f73578497a6c3cc77bcbfd2e5bf15fe753c7 upstream.
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: 97548575bef3 ("mmc: block: Convert RPMB to a character device") Reported-by: Adrian Hunter adrian.hunter@intel.com Signed-off-by: Linus Walleij linus.walleij@linaro.org Acked-by: Adrian Hunter adrian.hunter@intel.com Signed-off-by: Ulf Hansson ulf.hansson@linaro.org Cc: Jisheng Zhang Jisheng.Zhang@synaptics.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/mmc/core/block.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-)
--- a/drivers/mmc/core/block.c +++ b/drivers/mmc/core/block.c @@ -2323,9 +2323,7 @@ static int mmc_rpmb_chrdev_open(struct i
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); } @@ -2336,9 +2334,7 @@ static int mmc_rpmb_chrdev_release(struc 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; } @@ -2354,6 +2350,13 @@ static const struct file_operations mmc_ #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, @@ -2372,8 +2375,10 @@ static int mmc_blk_alloc_rpmb_part(struc 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 : ""); @@ -2384,6 +2389,7 @@ static int mmc_blk_alloc_rpmb_part(struc 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; @@ -2393,7 +2399,7 @@ static int mmc_blk_alloc_rpmb_part(struc 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); @@ -2408,18 +2414,16 @@ static int mmc_blk_alloc_rpmb_part(struc
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