From: Kees Cook <keescook@chromium.org>
Date: Fri, 22 Sep 2023 17:53:19 +0000 (-0700)
Subject: cxl/acpi: Annotate struct cxl_cxims_data with __counted_by
X-Git-Tag: microblaze-v6.8~401^2
X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=c66650d29764e228eba40b7a59fdb70fa6567daa;p=linux-2.6-microblaze.git

cxl/acpi: Annotate struct cxl_cxims_data 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 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: Vishal Verma <vishal.l.verma@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20230922175319.work.096-kees@kernel.org
Signed-off-by: Dan Williams <dan.j.williams@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;