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
[ 20.627288] mmc_rpmb mmcblk3rpmb: removed
Fixes: 0ab0c7c0e65a ("mmc: block: Convert RPMB to a character device")
Reported-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
drivers/mmc/core/block.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index c29dbcec7c61..2033a71bacc3 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -2329,6 +2329,14 @@ 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);
+
+ dev_info(dev, "removed\n");
+ 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,
@@ -2371,6 +2379,8 @@ static int mmc_blk_alloc_rpmb_part(struct mmc_card *card,
goto out_remove_ida;
}
+ /* From this point, the .release() function cleans up the device */
+ rpmb->dev.release = mmc_blk_rpmb_device_release;
list_add(&rpmb->node, &md->rpmbs);
string_get_size((u64)size, 512, STRING_UNITS_2,
@@ -2384,17 +2394,22 @@ static int mmc_blk_alloc_rpmb_part(struct mmc_card *card,
return 0;
out_remove_ida:
+ put_device(&rpmb->dev);
ida_simple_remove(&mmc_rpmb_ida, rpmb->id);
kfree(rpmb);
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);
+ /*
+ * Unless something is holding a reference to the device, this
+ * drops the last reference and triggers the device to cleanup
+ * and calls the .remove() callback.
+ */
+ put_device(&rpmb->dev);
}
/* MMC Physical partitions consist of two boot partitions and
--
2.13.5
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