This is a note to let you know that I've just added the patch titled
mfd: mfd-core: Protect against NULL call-back function pointer
to the 4.9-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:
mfd-mfd-core-protect-against-null-call-back-function.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a1924f241d66df0f3db694ba79de26fd23a6c518
Author: Lee Jones <lee.jones@xxxxxxxxxx>
Date: Mon Oct 21 10:16:34 2019 +0100
mfd: mfd-core: Protect against NULL call-back function pointer
[ Upstream commit b195e101580db390f50b0d587b7f66f241d2bc88 ]
If a child device calls mfd_cell_{en,dis}able() without an appropriate
call-back being set, we are likely to encounter a panic. Avoid this
by adding suitable checking.
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
Reviewed-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
Reviewed-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index 5c8ed2150c8bf..fb687368ac98c 100644
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -32,6 +32,11 @@ int mfd_cell_enable(struct platform_device *pdev)
const struct mfd_cell *cell = mfd_get_cell(pdev);
int err = 0;
+ if (!cell->enable) {
+ dev_dbg(&pdev->dev, "No .enable() call-back registered\n");
+ return 0;
+ }
+
/* only call enable hook if the cell wasn't previously enabled */
if (atomic_inc_return(cell->usage_count) == 1)
err = cell->enable(pdev);
@@ -49,6 +54,11 @@ int mfd_cell_disable(struct platform_device *pdev)
const struct mfd_cell *cell = mfd_get_cell(pdev);
int err = 0;
+ if (!cell->disable) {
+ dev_dbg(&pdev->dev, "No .disable() call-back registered\n");
+ return 0;
+ }
+
/* only disable if no other clients are using it */
if (atomic_dec_return(cell->usage_count) == 0)
err = cell->disable(pdev);
