| Message ID | 57a831d94ee2b3889b11525d4ad500356f89576f.1697492890.git.gustavoars@kernel.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 5ad1e217a2b23aa046b241183bd9452d259d70d0 |
| Headers | show |
| Series | clk: visconti: Fix undefined behavior bug and add bounds-checking coverage | expand |
Quoting Gustavo A. R. Silva (2023-10-16 15:05:27) > `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 visconti_pll_provider`, in this case > `struct device_node *node;`, at run-time: > > drivers/clk/visconti/pll.h: > 16 struct visconti_pll_provider { > 17 void __iomem *reg_base; > 18 struct clk_hw_onecell_data clk_data; > 19 struct device_node *node; > 20 }; > > Notice that a total of 56 bytes are allocated for flexible-array `hws` > at line 328. See below: > > include/dt-bindings/clock/toshiba,tmpv770x.h: > 14 #define TMPV770X_NR_PLL 7 > > drivers/clk/visconti/pll-tmpv770x.c: > 69 ctx = visconti_init_pll(np, reg_base, TMPV770X_NR_PLL); > > drivers/clk/visconti/pll.c: > 321 struct visconti_pll_provider * __init visconti_init_pll(struct device_node *np, > 322 void __iomem *base, > 323 unsigned long nr_plls) > 324 { > 325 struct visconti_pll_provider *ctx; > ... > 328 ctx = kzalloc(struct_size(ctx, clk_data.hws, nr_plls), GFP_KERNEL); > > `struct_size(ctx, clk_data.hws, nr_plls)` above translates to > sizeof(struct visconti_pll_provider) + sizeof(struct clk_hw *) * 7 == > 24 + 8 * 7 == 24 + 56 > ^^^^ > | > allocated bytes for flex array `hws` > > $ pahole -C visconti_pll_provider drivers/clk/visconti/pll.o > struct visconti_pll_provider { > void * reg_base; /* 0 8 */ > struct clk_hw_onecell_data clk_data; /* 8 8 */ > struct device_node * node; /* 16 8 */ > > /* size: 24, cachelines: 1, members: 3 */ > /* last cacheline: 24 bytes */ > }; > > And then, after the allocation, some data is written into all members > of `struct visconti_pll_provider`: > > 332 for (i = 0; i < nr_plls; ++i) > 333 ctx->clk_data.hws[i] = ERR_PTR(-ENOENT); > 334 > 335 ctx->node = np; > 336 ctx->reg_base = base; > 337 ctx->clk_data.num = nr_plls; > > Fix all these by placing the declaration of object `clk_data` at the > end of `struct visconti_pll_provider`. Also, add a comment to make it > clear that this object must always be last in the structure, and > prevent this bug from being introduced again in the future. > > -Wflex-array-member-not-at-end is coming in GCC-14, and we are getting > ready to enable it globally. > > Fixes: b4cbe606dc36 ("clk: visconti: Add support common clock driver and reset driver") > Cc: stable@vger.kernel.org > Reviewed-by: Kees Cook <keescook@chromium.org> > Acked-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp> > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> > --- Applied to clk-next
>> Fixes: b4cbe606dc36 ("clk: visconti: Add support common clock driver and reset driver") >> Cc: stable@vger.kernel.org >> Reviewed-by: Kees Cook <keescook@chromium.org> >> Acked-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp> >> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> >> --- > > Applied to clk-next Hi! Here is another similar small series, in case you missed it: https://lore.kernel.org/linux-hardening/cover.1697493574.git.gustavoars@kernel.org/ Thanks -- Gustavo
Quoting Gustavo A. R. Silva (2023-10-23 19:48:00) > > >> Fixes: b4cbe606dc36 ("clk: visconti: Add support common clock driver and reset driver") > >> Cc: stable@vger.kernel.org > >> Reviewed-by: Kees Cook <keescook@chromium.org> > >> Acked-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp> > >> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> > >> --- > > > > Applied to clk-next > > Hi! > > Here is another similar small series, in case you missed it: > > https://lore.kernel.org/linux-hardening/cover.1697493574.git.gustavoars@kernel.org/ > Please Cc linux-clk on clk patches.
diff --git a/drivers/clk/visconti/pll.h b/drivers/clk/visconti/pll.h index 01d07f1bf01b..c4bd40676da4 100644 --- a/drivers/clk/visconti/pll.h +++ b/drivers/clk/visconti/pll.h @@ -15,8 +15,10 @@ struct visconti_pll_provider { void __iomem *reg_base; - struct clk_hw_onecell_data clk_data; struct device_node *node; + + /* Must be last */ + struct clk_hw_onecell_data clk_data; }; #define VISCONTI_PLL_RATE(_rate, _dacen, _dsmen, \
`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 visconti_pll_provider`, in this case `struct device_node *node;`, at run-time: drivers/clk/visconti/pll.h: 16 struct visconti_pll_provider { 17 void __iomem *reg_base; 18 struct clk_hw_onecell_data clk_data; 19 struct device_node *node; 20 }; Notice that a total of 56 bytes are allocated for flexible-array `hws` at line 328. See below: include/dt-bindings/clock/toshiba,tmpv770x.h: 14 #define TMPV770X_NR_PLL 7 drivers/clk/visconti/pll-tmpv770x.c: 69 ctx = visconti_init_pll(np, reg_base, TMPV770X_NR_PLL); drivers/clk/visconti/pll.c: 321 struct visconti_pll_provider * __init visconti_init_pll(struct device_node *np, 322 void __iomem *base, 323 unsigned long nr_plls) 324 { 325 struct visconti_pll_provider *ctx; ... 328 ctx = kzalloc(struct_size(ctx, clk_data.hws, nr_plls), GFP_KERNEL); `struct_size(ctx, clk_data.hws, nr_plls)` above translates to sizeof(struct visconti_pll_provider) + sizeof(struct clk_hw *) * 7 == 24 + 8 * 7 == 24 + 56 ^^^^ | allocated bytes for flex array `hws` $ pahole -C visconti_pll_provider drivers/clk/visconti/pll.o struct visconti_pll_provider { void * reg_base; /* 0 8 */ struct clk_hw_onecell_data clk_data; /* 8 8 */ struct device_node * node; /* 16 8 */ /* size: 24, cachelines: 1, members: 3 */ /* last cacheline: 24 bytes */ }; And then, after the allocation, some data is written into all members of `struct visconti_pll_provider`: 332 for (i = 0; i < nr_plls; ++i) 333 ctx->clk_data.hws[i] = ERR_PTR(-ENOENT); 334 335 ctx->node = np; 336 ctx->reg_base = base; 337 ctx->clk_data.num = nr_plls; Fix all these by placing the declaration of object `clk_data` at the end of `struct visconti_pll_provider`. Also, add a comment to make it clear that this object must always be last in the structure, and prevent this bug from being introduced again in the future. -Wflex-array-member-not-at-end is coming in GCC-14, and we are getting ready to enable it globally. Fixes: b4cbe606dc36 ("clk: visconti: Add support common clock driver and reset driver") Cc: stable@vger.kernel.org Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- Changes in v2: - Mention -Wflex-array-member-not-at-end in the changelog text. v1: - Link: https://lore.kernel.org/linux-hardening/0a59a721d54b557076cc94eabeb694d463773204.1697076650.git.gustavoars@kernel.org/ drivers/clk/visconti/pll.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)