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Message-ID: <ZQ8Zf0ckEeRwGr/X@work>
Date: Sat, 23 Sep 2023 10:59:43 -0600
From: "Gustavo A. R. Silva" <gustavoars@...nel.org>
To: Kees Cook <keescook@...omium.org>
Cc: Davidlohr Bueso <dave@...olabs.net>,
Jonathan Cameron <jonathan.cameron@...wei.com>,
Dave Jiang <dave.jiang@...el.com>,
Alison Schofield <alison.schofield@...el.com>,
Vishal Verma <vishal.l.verma@...el.com>,
Ira Weiny <ira.weiny@...el.com>,
Dan Williams <dan.j.williams@...el.com>,
linux-cxl@...r.kernel.org, Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Tom Rix <trix@...hat.com>, linux-kernel@...r.kernel.org,
llvm@...ts.linux.dev, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] cxl/acpi: Annotate struct cxl_cxims_data with
__counted_by
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@...olabs.net>
> Cc: Jonathan Cameron <jonathan.cameron@...wei.com>
> Cc: Dave Jiang <dave.jiang@...el.com>
> Cc: Alison Schofield <alison.schofield@...el.com>
> Cc: Vishal Verma <vishal.l.verma@...el.com>
> Cc: Ira Weiny <ira.weiny@...el.com>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: linux-cxl@...r.kernel.org
> Signed-off-by: Kees Cook <keescook@...omium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@...nel.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
>
>
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