[tip: x86/platform] x86/platform/uv: Annotate struct uv_rtc_timer_head with __counted_by

[tip-bot2 for Kees Cook]

The following commit has been merged into the x86/platform branch of tip:

Commit-ID:     d9a01959d9c954c8fe1d132b52401b0e219e37f6
Gitweb:        https://git.kernel.org/tip/d9a01959d9c954c8fe1d132b52401b0e219e37f6
Author:        Kees Cook <keescook@xxxxxxxxxxxx>
AuthorDate:    Fri, 22 Sep 2023 10:51:51 -07:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Sun, 24 Sep 2023 12:02:58 +02:00

x86/platform/uv: Annotate struct uv_rtc_timer_head 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).

Found with Coccinelle:

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

Add __counted_by for struct uv_rtc_timer_head.

Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230922175151.work.118-kees@xxxxxxxxxx
---
 arch/x86/platform/uv/uv_time.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/platform/uv/uv_time.c b/arch/x86/platform/uv/uv_time.c
index 54663f3..ff5afc8 100644
--- a/arch/x86/platform/uv/uv_time.c
+++ b/arch/x86/platform/uv/uv_time.c
@@ -53,7 +53,7 @@ struct uv_rtc_timer_head {
 	struct {
 		int	lcpu;		/* systemwide logical cpu number */
 		u64	expires;	/* next timer expiration for this cpu */
-	} cpu[];
+	} cpu[] __counted_by(ncpus);
 };
 
 /*