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author | Martin Blumenstingl <martin.blumenstingl@googlemail.com> | 2019-08-16 01:31:55 +0300 |
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committer | Stephen Boyd <sboyd@kernel.org> | 2019-08-16 20:30:21 +0300 |
commit | 24876f09a7dfe36a82f53d304d8c1bceb3257a0f (patch) | |
tree | b944db8adddab773d7e7e636c27f0aef031793cf /drivers/clk | |
parent | 4f8c6aba37da199155a121c6cdc38505a9eb0259 (diff) | |
download | linux-24876f09a7dfe36a82f53d304d8c1bceb3257a0f.tar.xz |
clk: Fix potential NULL dereference in clk_fetch_parent_index()
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@googlemail.com>
Link: https://lkml.kernel.org/r/20190815223155.21384-1-martin.blumenstingl@googlemail.com
Fixes: fc0c209c147f ("clk: Allow parents to be specified without string names")
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Diffstat (limited to 'drivers/clk')
-rw-r--r-- | drivers/clk/clk.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 8bce6bb4a965..1c46babeb093 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1654,7 +1654,8 @@ 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; } |