| Message ID | 5dd8483177dc8cd91d021170b6717f2e570bab03.1697059539.git.gustavoars@kernel.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | d761bb01c85b22d5b44abe283eb89019693f6595 |
| Headers | show |
| Series | Fix undefined behavior bug and add bounds-checking coverage | expand |
On Wed, Oct 11, 2023 at 03:34:03PM -0600, Gustavo A. R. Silva wrote: > `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. > > Fixes: ba7e258425ac ("clk: socfpga: Convert to s10/agilex/n5x to use clk_hw") > Cc: stable@vger.kernel.org > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Nice find! Reviewed-by: Kees Cook <keescook@chromium.org>
>> Fixes: ba7e258425ac ("clk: socfpga: Convert to s10/agilex/n5x to use clk_hw") >> Cc: stable@vger.kernel.org >> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> > > Nice find! :D > > Reviewed-by: Kees Cook <keescook@chromium.org> > Thanks! -- Gustavo
diff --git a/drivers/clk/socfpga/stratix10-clk.h b/drivers/clk/socfpga/stratix10-clk.h index 75234e0783e1..83fe4eb3133c 100644 --- a/drivers/clk/socfpga/stratix10-clk.h +++ b/drivers/clk/socfpga/stratix10-clk.h @@ -7,8 +7,10 @@ #define __STRATIX10_CLK_H struct stratix10_clock_data { - struct clk_hw_onecell_data clk_data; void __iomem *base; + + /* Must be last */ + struct clk_hw_onecell_data clk_data; }; struct stratix10_pll_clock {
`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. Fixes: ba7e258425ac ("clk: socfpga: Convert to s10/agilex/n5x to use clk_hw") Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- drivers/clk/socfpga/stratix10-clk.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)