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@vger.kernel.org Suggested-by: Viresh Kumar viresh.kumar@linaro.org Fixes: 7eba0c7641b0 ("opp: Allow lazy-linking of required-opps") Signed-off-by: Stephan Gerhold stephan.gerhold@kernkonzept.com
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@kernkonzep...
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.