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mfd: mfd-core: Protect against NULL call-back function pointer 

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@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Lee Jones 2019-10-21 10:16:34 +01:00
parent 99cd105975
commit b195e10158
1 changed files with 10 additions and 0 deletions
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10
drivers/mfd/mfd-core.c
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@ -28,6 +28,11 @@ 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);
@ -45,6 +50,11 @@ 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);