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d761bb01c8
`struct clk_hw_onecell_data` is a flexible structure, which means that
it contains flexible-array member at the bottom, in this case array
`hws`:
include/linux/clk-provider.h:
1380 struct clk_hw_onecell_data {
1381 unsigned int num;
1382 struct clk_hw *hws[] __counted_by(num);
1383 };
This could potentially lead to an overwrite of the objects following
`clk_data` in `struct stratix10_clock_data`, in this case
`void __iomem *base;` at run-time:
drivers/clk/socfpga/stratix10-clk.h:
9 struct stratix10_clock_data {
10 struct clk_hw_onecell_data clk_data;
11 void __iomem *base;
12 };
There are currently three different places where memory is allocated for
`struct stratix10_clock_data`, including the flex-array `hws` in
`struct clk_hw_onecell_data`:
drivers/clk/socfpga/clk-agilex.c:
469 clk_data = devm_kzalloc(dev, struct_size(clk_data, clk_data.hws,
470 num_clks), GFP_KERNEL);
drivers/clk/socfpga/clk-agilex.c:
509 clk_data = devm_kzalloc(dev, struct_size(clk_data, clk_data.hws,
510 num_clks), GFP_KERNEL);
drivers/clk/socfpga/clk-s10.c:
400 clk_data = devm_kzalloc(dev, struct_size(clk_data, clk_data.hws,
401 num_clks), GFP_KERNEL);
I'll use just one of them to describe the issue. See below.
Notice that a total of 440 bytes are allocated for flexible-array member
`hws` at line 469:
include/dt-bindings/clock/agilex-clock.h:
70 #define AGILEX_NUM_CLKS 55
drivers/clk/socfpga/clk-agilex.c:
459 struct stratix10_clock_data *clk_data;
460 void __iomem *base;
...
466
467 num_clks = AGILEX_NUM_CLKS;
468
469 clk_data = devm_kzalloc(dev, struct_size(clk_data, clk_data.hws,
470 num_clks), GFP_KERNEL);
`struct_size(clk_data, clk_data.hws, num_clks)` above translates to
sizeof(struct stratix10_clock_data) + sizeof(struct clk_hw *) * 55 ==
16 + 8 * 55 == 16 + 440
^^^
|
allocated bytes for flex-array `hws`
474 for (i = 0; i < num_clks; i++)
475 clk_data->clk_data.hws[i] = ERR_PTR(-ENOENT);
476
477 clk_data->base = base;
and then some data is written into both `hws` and `base` objects.
Fix this by placing the declaration of object `clk_data` at the end of
`struct stratix10_clock_data`. Also, add a comment to make it clear
that this object must always be last in the structure.
-Wflex-array-member-not-at-end is coming in GCC-14, and we are getting
ready to enable it globally.
Fixes:
|
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Linux kernel
============
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There are various text files in the Documentation/ subdirectory,
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