2023-09-22 21:26:11

by Kees Cook

Subject: [PATCH] module: Annotate struct module_notes_attrs with __counted_by

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct module_notes_attrs.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Luis Chamberlain <[email protected]>
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
kernel/module/sysfs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/module/sysfs.c b/kernel/module/sysfs.c
index c921bf044050..d964167c6658 100644
--- a/kernel/module/sysfs.c
+++ b/kernel/module/sysfs.c
@@ -143,7 +143,7 @@ static void remove_sect_attrs(struct module *mod)
struct module_notes_attrs {
struct kobject *dir;
unsigned int notes;
- struct bin_attribute attrs[];
+ struct bin_attribute attrs[] __counted_by(notes);
};

static ssize_t module_notes_read(struct file *filp, struct kobject *kobj,
--
2.34.1

2023-09-23 01:34:17

by Luis Chamberlain

Subject: Re: [PATCH] module: Annotate struct module_notes_attrs with __counted_by

On Fri, Sep 22, 2023 at 10:52:53AM -0700, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> As found with Coccinelle[1], add __counted_by for struct module_notes_attrs.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Luis Chamberlain <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>

Thanks, applied and pushed!

Luis

2023-09-23 09:00:49

by Gustavo A. R. Silva

Subject: Re: [PATCH] module: Annotate struct module_notes_attrs with __counted_by

On Fri, Sep 22, 2023 at 10:52:53AM -0700, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> As found with Coccinelle[1], add __counted_by for struct module_notes_attrs.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Luis Chamberlain <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>

Reviewed-by: Gustavo A. R. Silva <[email protected]>

Thanks
--
Gustavo

> ---
> kernel/module/sysfs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/module/sysfs.c b/kernel/module/sysfs.c
> index c921bf044050..d964167c6658 100644
> --- a/kernel/module/sysfs.c
> +++ b/kernel/module/sysfs.c
> @@ -143,7 +143,7 @@ static void remove_sect_attrs(struct module *mod)
> struct module_notes_attrs {
> struct kobject *dir;
> unsigned int notes;
> - struct bin_attribute attrs[];
> + struct bin_attribute attrs[] __counted_by(notes);
> };
>
> static ssize_t module_notes_read(struct file *filp, struct kobject *kobj,
> --
> 2.34.1
>
>