From: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx> [ Upstream commit 24876f09a7dfe36a82f53d304d8c1bceb3257a0f ] Don't compare the parent clock name with a NULL name in the clk_parent_map. This prevents a kernel crash when passing NULL core->parents[i].name to strcmp(). An example which triggered this is a mux clock with four parents when each of them is referenced in the clock driver using clk_parent_data.fw_name and then calling clk_set_parent(clk, 3rd_parent) on this mux. In this case the first parent is also the HW default so core->parents[i].hw is populated when the clock is registered. Calling clk_set_parent(clk, 3rd_parent) will then go through all parents and skip the first parent because it's hw pointer doesn't match. For the second parent no hw pointer is cached yet and clk_core_get(core, 1) returns a non-matching pointer (which is correct because we are comparing the second with the third parent). Comparing the result of clk_core_get(core, 2) with the requested parent gives a match. However we don't reach this point because right after the clk_core_get(core, 1) mismatch the old code tried to !strcmp(parent->name, NULL) (where the second argument is actually core->parents[i].name, but that was never populated by the clock driver). Signed-off-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20190815223155.21384-1-martin.blumenstingl@xxxxxxxxxxxxxx Fixes: fc0c209c147f ("clk: Allow parents to be specified without string names") Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/clk/clk.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 498cd7bbe8984..3a4961dc58313 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1657,7 +1657,8 @@ static int clk_fetch_parent_index(struct clk_core *core, break; /* Fallback to comparing globally unique names */ - if (!strcmp(parent->name, core->parents[i].name)) + if (core->parents[i].name && + !strcmp(parent->name, core->parents[i].name)) break; } -- 2.20.1
