Patch "clk: Fix clk_core_get NULL dereference" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    clk: Fix clk_core_get NULL dereference

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     clk-fix-clk_core_get-null-dereference.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit ea794b69f8e70c49a383672b7dd8b5ba424f3d0d
Author: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx>
Date:   Sat Mar 2 00:52:14 2024 +0000

    clk: Fix clk_core_get NULL dereference
    
    [ Upstream commit e97fe4901e0f59a0bfd524578fe3768f8ca42428 ]
    
    It is possible for clk_core_get to dereference a NULL in the following
    sequence:
    
    clk_core_get()
        of_clk_get_hw_from_clkspec()
            __of_clk_get_hw_from_provider()
                __clk_get_hw()
    
    __clk_get_hw() can return NULL which is dereferenced by clk_core_get() at
    hw->core.
    
    Prior to commit dde4eff47c82 ("clk: Look for parents with clkdev based
    clk_lookups") the check IS_ERR_OR_NULL() was performed which would have
    caught the NULL.
    
    Reading the description of this function it talks about returning NULL but
    that cannot be so at the moment.
    
    Update the function to check for hw before dereferencing it and return NULL
    if hw is NULL.
    
    Fixes: dde4eff47c82 ("clk: Look for parents with clkdev based clk_lookups")
    Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240302-linux-next-24-03-01-simple-clock-fixes-v1-1-25f348a5982b@xxxxxxxxxx
    Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 473563bc74960..50228cb0c5590 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -418,6 +418,9 @@ static struct clk_core *clk_core_get(struct clk_core *core, u8 p_index)
 	if (IS_ERR(hw))
 		return ERR_CAST(hw);
 
+	if (!hw)
+		return NULL;
+
 	return hw->core;
 }