On 30-05-23, 17:54, Stephan Gerhold wrote:
> When dev_pm_opp_of_find_icc_paths() in _allocate_opp_table() returns
> -EPROBE_DEFER, the opp_table is freed again, to wait until all the
> interconnect paths are available.
>
> However, if the OPP table is using required-opps then it may already
> have been added to the global lazy_opp_tables list. The error path
> does not remove the opp_table from the list again.
>
> This can cause crashes later when the provider of the required-opps
> is added, since we will iterate over OPP tables that have already been
> freed. E.g.:
>
> Unable to handle kernel NULL pointer dereference when read
> CPU: 0 PID: 7 Comm: kworker/0:0 Not tainted 6.4.0-rc3
> PC is at _of_add_opp_table_v2 (include/linux/of.h:949
> drivers/opp/of.c:98 drivers/opp/of.c:344 drivers/opp/of.c:404
> drivers/opp/of.c:1032) -> lazy_link_required_opp_table()
>
> Fix this by calling _of_clear_opp_table() to remove the opp_table from
> the list and clear other allocated resources. While at it, also add the
> missing mutex_destroy() calls in the error path.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Suggested-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> Fixes: 7eba0c7641b0 ("opp: Allow lazy-linking of required-opps")
> Signed-off-by: Stephan Gerhold <stephan.gerhold@xxxxxxxxxxxxxxx>
> ---
> Changes in v2:
> - Call _of_clear_opp_table() as suggested by Viresh
> - Also add missing mutex_destroy() calls in the error path
> - Link to v1: https://lore.kernel.org/r/20230524-opp-lazy-uaf-v1-1-f5f95cb4b6de@xxxxxxxxxxxxxxx
> ---
> This fixes the crash I ran into after adding an OPP table with
> both "required-opps" and interconnect paths (opp-peak-kBps).
> ---
> drivers/opp/core.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 85cbc8de407c..7046487dc6f4 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1358,7 +1358,10 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index)
> return opp_table;
>
> remove_opp_dev:
> + _of_clear_opp_table(opp_table);
> _remove_opp_dev(opp_dev, opp_table);
> + mutex_destroy(&opp_table->genpd_virt_dev_lock);
> + mutex_destroy(&opp_table->lock);
> err:
> kfree(opp_table);
> return ERR_PTR(ret);
>
Applied. Thanks.
--
viresh
