| Message ID | ZzZ-cd_EFXs6qFaH@kspp (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
| Series | clk: clk-loongson2: Fix memory corruption bug in struct loongson2_clk_provider | expand |
Quoting Gustavo A. R. Silva (2024-11-14 14:49:21) > Some heap space is allocated for the flexible structure `struct > clk_hw_onecell_data` and its flexible-array member `hws` through > the composite structure `struct loongson2_clk_provider` in function > `loongson2_clk_probe()`, as shown below: > > 289 struct loongson2_clk_provider *clp; > ... > 296 for (p = data; p->name; p++) > 297 clks_num++; > 298 > 299 clp = devm_kzalloc(dev, struct_size(clp, clk_data.hws, clks_num), > 300 GFP_KERNEL); > > Then some data is written into the flexible array: > > 350 clp->clk_data.hws[p->id] = hw; > > This corrupts `clk_lock`, which is the spinlock variable immediately > following the `clk_data` member in `struct loongson2_clk_provider`: > > struct loongson2_clk_provider { > void __iomem *base; > struct device *dev; > struct clk_hw_onecell_data clk_data; > spinlock_t clk_lock; /* protect access to DIV registers */ > }; > > The problem is that the flexible structure is currently placed in the > middle of `struct loongson2_clk_provider` instead of at the end. > > Fix this by moving `struct clk_hw_onecell_data clk_data;` to the end of > `struct loongson2_clk_provider`. Also, add a code comment to help > prevent this from happening again in case new members are added to the > structure in the future. > > This change also fixes the following -Wflex-array-member-not-at-end > warning: > > drivers/clk/clk-loongson2.c:32:36: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > > Fixes: 9796ec0bd04b ("clk: clk-loongson2: Refactor driver for adding new platforms") > Cc: stable@vger.kernel.org > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> > --- Applied to clk-next
diff --git a/drivers/clk/clk-loongson2.c b/drivers/clk/clk-loongson2.c index 820bb1e9e3b7..e99ba79feec6 100644 --- a/drivers/clk/clk-loongson2.c +++ b/drivers/clk/clk-loongson2.c @@ -29,8 +29,10 @@ enum loongson2_clk_type { struct loongson2_clk_provider { void __iomem *base; struct device *dev; - struct clk_hw_onecell_data clk_data; spinlock_t clk_lock; /* protect access to DIV registers */ + + /* Must be last --ends in a flexible-array member. */ + struct clk_hw_onecell_data clk_data; }; struct loongson2_clk_data {
Some heap space is allocated for the flexible structure `struct clk_hw_onecell_data` and its flexible-array member `hws` through the composite structure `struct loongson2_clk_provider` in function `loongson2_clk_probe()`, as shown below: 289 struct loongson2_clk_provider *clp; ... 296 for (p = data; p->name; p++) 297 clks_num++; 298 299 clp = devm_kzalloc(dev, struct_size(clp, clk_data.hws, clks_num), 300 GFP_KERNEL); Then some data is written into the flexible array: 350 clp->clk_data.hws[p->id] = hw; This corrupts `clk_lock`, which is the spinlock variable immediately following the `clk_data` member in `struct loongson2_clk_provider`: struct loongson2_clk_provider { void __iomem *base; struct device *dev; struct clk_hw_onecell_data clk_data; spinlock_t clk_lock; /* protect access to DIV registers */ }; The problem is that the flexible structure is currently placed in the middle of `struct loongson2_clk_provider` instead of at the end. Fix this by moving `struct clk_hw_onecell_data clk_data;` to the end of `struct loongson2_clk_provider`. Also, add a code comment to help prevent this from happening again in case new members are added to the structure in the future. This change also fixes the following -Wflex-array-member-not-at-end warning: drivers/clk/clk-loongson2.c:32:36: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] Fixes: 9796ec0bd04b ("clk: clk-loongson2: Refactor driver for adding new platforms") Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- drivers/clk/clk-loongson2.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)