[PATCH] nexthop: Annotate struct nh_notifier_grp_info with __counted_by

Kees Cook
2023-10-03T23:21:54Z

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 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 nh_notifier_grp_info.

Cc: David Ahern <dsahern@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Tom Rix <trix@redhat.com>
Cc: netdev@vger.kernel.org
Cc: llvm@lists.linux.dev
Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1]
Signed-off-by: Kees Cook <keescook@chromium.org>
---
include/net/nexthop.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/nexthop.h b/include/net/nexthop.h
index 2b12725de9c0..5dc4b4bba8a5 100644
--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -187,7 +187,7 @@ struct nh_notifier_grp_entry_info {
struct nh_notifier_grp_info {
u16 num_nh;
bool is_fdb;
- struct nh_notifier_grp_entry_info nh_entries[];
+ struct nh_notifier_grp_entry_info nh_entries[] __counted_by(num_nh);
};

struct nh_notifier_res_bucket_info {
--
2.34.1