diff mbox series

cxl/acpi: Annotate struct cxl_cxims_data with __counted_by

Message ID 20230922175319.work.096-kees@kernel.org (mailing list archive)
State Mainlined
Commit c66650d29764e228eba40b7a59fdb70fa6567daa
Headers show
Series cxl/acpi: Annotate struct cxl_cxims_data with __counted_by | expand

Commit Message

Kees Cook Sept. 22, 2023, 5:53 p.m. UTC
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 cxl_cxims_data.
Additionally, since the element count member must be set before accessing
the annotated flexible array member, move its initialization earlier.

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

Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: linux-cxl@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/cxl/acpi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Dave Jiang Sept. 22, 2023, 6:05 p.m. UTC | #1
On 9/22/23 10:53, 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 cxl_cxims_data.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Davidlohr Bueso <dave@stgolabs.net>
> Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
> Cc: Dave Jiang <dave.jiang@intel.com>
> Cc: Alison Schofield <alison.schofield@intel.com>
> Cc: Vishal Verma <vishal.l.verma@intel.com>
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: linux-cxl@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  drivers/cxl/acpi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index d1c559879dcc..40d055560e52 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -14,7 +14,7 @@
>  
>  struct cxl_cxims_data {
>  	int nr_maps;
> -	u64 xormaps[];
> +	u64 xormaps[] __counted_by(nr_maps);
>  };
>  
>  /*
> @@ -112,9 +112,9 @@ static int cxl_parse_cxims(union acpi_subtable_headers *header, void *arg,
>  			      GFP_KERNEL);
>  	if (!cximsd)
>  		return -ENOMEM;
> +	cximsd->nr_maps = nr_maps;
>  	memcpy(cximsd->xormaps, cxims->xormap_list,
>  	       nr_maps * sizeof(*cximsd->xormaps));
> -	cximsd->nr_maps = nr_maps;
>  	cxlrd->platform_data = cximsd;
>  
>  	return 0;
Verma, Vishal L Sept. 22, 2023, 6:25 p.m. UTC | #2
On Fri, 2023-09-22 at 10:53 -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 cxl_cxims_data.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Davidlohr Bueso <dave@stgolabs.net>
> Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
> Cc: Dave Jiang <dave.jiang@intel.com>
> Cc: Alison Schofield <alison.schofield@intel.com>
> Cc: Vishal Verma <vishal.l.verma@intel.com>
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: linux-cxl@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  drivers/cxl/acpi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>

> 
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index d1c559879dcc..40d055560e52 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -14,7 +14,7 @@
>  
>  struct cxl_cxims_data {
>         int nr_maps;
> -       u64 xormaps[];
> +       u64 xormaps[] __counted_by(nr_maps);
>  };
>  
>  /*
> @@ -112,9 +112,9 @@ static int cxl_parse_cxims(union acpi_subtable_headers *header, void *arg,
>                               GFP_KERNEL);
>         if (!cximsd)
>                 return -ENOMEM;
> +       cximsd->nr_maps = nr_maps;
>         memcpy(cximsd->xormaps, cxims->xormap_list,
>                nr_maps * sizeof(*cximsd->xormaps));
> -       cximsd->nr_maps = nr_maps;
>         cxlrd->platform_data = cximsd;
>  
>         return 0;
Gustavo A. R. Silva Sept. 23, 2023, 4:59 p.m. UTC | #3
On Fri, Sep 22, 2023 at 10:53:19AM -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 cxl_cxims_data.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Davidlohr Bueso <dave@stgolabs.net>
> Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
> Cc: Dave Jiang <dave.jiang@intel.com>
> Cc: Alison Schofield <alison.schofield@intel.com>
> Cc: Vishal Verma <vishal.l.verma@intel.com>
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: linux-cxl@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
--
Gustavo

> ---
>  drivers/cxl/acpi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index d1c559879dcc..40d055560e52 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -14,7 +14,7 @@
>  
>  struct cxl_cxims_data {
>  	int nr_maps;
> -	u64 xormaps[];
> +	u64 xormaps[] __counted_by(nr_maps);
>  };
>  
>  /*
> @@ -112,9 +112,9 @@ static int cxl_parse_cxims(union acpi_subtable_headers *header, void *arg,
>  			      GFP_KERNEL);
>  	if (!cximsd)
>  		return -ENOMEM;
> +	cximsd->nr_maps = nr_maps;
>  	memcpy(cximsd->xormaps, cxims->xormap_list,
>  	       nr_maps * sizeof(*cximsd->xormaps));
> -	cximsd->nr_maps = nr_maps;
>  	cxlrd->platform_data = cximsd;
>  
>  	return 0;
> -- 
> 2.34.1
> 
>
Davidlohr Bueso Sept. 28, 2023, 1:18 a.m. UTC | #4
On Fri, 22 Sep 2023, 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 cxl_cxims_data.
>Additionally, since the element count member must be set before accessing
>the annotated flexible array member, move its initialization earlier.

Nice.

Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>

>
>[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
>Cc: Davidlohr Bueso <dave@stgolabs.net>
>Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
>Cc: Dave Jiang <dave.jiang@intel.com>
>Cc: Alison Schofield <alison.schofield@intel.com>
>Cc: Vishal Verma <vishal.l.verma@intel.com>
>Cc: Ira Weiny <ira.weiny@intel.com>
>Cc: Dan Williams <dan.j.williams@intel.com>
>Cc: linux-cxl@vger.kernel.org
>Signed-off-by: Kees Cook <keescook@chromium.org>
>---
> drivers/cxl/acpi.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
>index d1c559879dcc..40d055560e52 100644
>--- a/drivers/cxl/acpi.c
>+++ b/drivers/cxl/acpi.c
>@@ -14,7 +14,7 @@
>
> struct cxl_cxims_data {
>	int nr_maps;
>-	u64 xormaps[];
>+	u64 xormaps[] __counted_by(nr_maps);
> };
>
> /*
>@@ -112,9 +112,9 @@ static int cxl_parse_cxims(union acpi_subtable_headers *header, void *arg,
>			      GFP_KERNEL);
>	if (!cximsd)
>		return -ENOMEM;
>+	cximsd->nr_maps = nr_maps;
>	memcpy(cximsd->xormaps, cxims->xormap_list,
>	       nr_maps * sizeof(*cximsd->xormaps));
>-	cximsd->nr_maps = nr_maps;
>	cxlrd->platform_data = cximsd;
>
>	return 0;
>--
>2.34.1
>
Justin Stitt Sept. 28, 2023, 4:48 a.m. UTC | #5
On Sat, Sep 23, 2023 at 2:53 AM Kees Cook <keescook@chromium.org> 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 cxl_cxims_data.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Davidlohr Bueso <dave@stgolabs.net>
> Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
> Cc: Dave Jiang <dave.jiang@intel.com>
> Cc: Alison Schofield <alison.schofield@intel.com>
> Cc: Vishal Verma <vishal.l.verma@intel.com>
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: linux-cxl@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Looks good.

The reordering of the count assignment is crucial here otherwise
the runtime checks will trip when `cximsd->xormaps` is used as
memcpy destination.

Reviewed-by: Justin Stitt <justinstitt@google.com>

> ---
>  drivers/cxl/acpi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index d1c559879dcc..40d055560e52 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -14,7 +14,7 @@
>
>  struct cxl_cxims_data {
>         int nr_maps;
> -       u64 xormaps[];
> +       u64 xormaps[] __counted_by(nr_maps);
>  };
>
>  /*
> @@ -112,9 +112,9 @@ static int cxl_parse_cxims(union acpi_subtable_headers *header, void *arg,
>                               GFP_KERNEL);
>         if (!cximsd)
>                 return -ENOMEM;
> +       cximsd->nr_maps = nr_maps;
>         memcpy(cximsd->xormaps, cxims->xormap_list,
>                nr_maps * sizeof(*cximsd->xormaps));
> -       cximsd->nr_maps = nr_maps;
>         cxlrd->platform_data = cximsd;
>
>         return 0;
> --
> 2.34.1
>
>
diff mbox series

Patch

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index d1c559879dcc..40d055560e52 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -14,7 +14,7 @@ 
 
 struct cxl_cxims_data {
 	int nr_maps;
-	u64 xormaps[];
+	u64 xormaps[] __counted_by(nr_maps);
 };
 
 /*
@@ -112,9 +112,9 @@  static int cxl_parse_cxims(union acpi_subtable_headers *header, void *arg,
 			      GFP_KERNEL);
 	if (!cximsd)
 		return -ENOMEM;
+	cximsd->nr_maps = nr_maps;
 	memcpy(cximsd->xormaps, cxims->xormap_list,
 	       nr_maps * sizeof(*cximsd->xormaps));
-	cximsd->nr_maps = nr_maps;
 	cxlrd->platform_data = cximsd;
 
 	return 0;