The "struct alg" object contains a union of 3 xfrm structures:
union {
struct xfrm_algo;
struct xfrm_algo_aead;
struct xfrm_algo_auth;
}
All of them end with a flexible array member used to store key material,
but the flexible array appears at *different offsets* in each struct.
bcz of this, union itself is of variable-sized & Placing it above
char buf[...] triggers:
ipsec.c:835:5: warning: field 'u' with variable sized type 'union
(unnamed union at ipsec.c:831:3)' not at the end of a struct or class
is a GNU extension [-Wgnu-variable-sized-type-not-at-end]
835 | } u;
| ^
one fix is to use "TRAILING_OVERLAP()" which works with one flexible
array member only.
But In "struct alg" flexible array member exists in all union members,
but not at the same offset, so TRAILING_OVERLAP cannot be applied.
so the fix is to explicitly overlay the key buffer at the correct offset
for the largest union member (xfrm_algo_auth). This ensures that the
flexible-array region and the fixed buffer line up.
No functional change.
Signed-off-by: Ankit Khushwaha <[email protected]>
---
tools/testing/selftests/net/ipsec.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/net/ipsec.c
b/tools/testing/selftests/net/ipsec.c
index 0ccf484b1d9d..f4afef51b930 100644
--- a/tools/testing/selftests/net/ipsec.c
+++ b/tools/testing/selftests/net/ipsec.c
@@ -43,6 +43,10 @@
#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
+#ifndef offsetof
+#define offsetof(TYPE, MEMBER) __builtin_offsetof(TYPE, MEMBER)
+#endif
+
#define IPV4_STR_SZ 16 /* xxx.xxx.xxx.xxx is longest + \0 */
#define MAX_PAYLOAD 2048
#define XFRM_ALGO_KEY_BUF_SIZE 512
@@ -827,13 +831,16 @@ static int xfrm_fill_key(char *name, char *buf,
static int xfrm_state_pack_algo(struct nlmsghdr *nh, size_t req_sz,
struct xfrm_desc *desc)
{
- struct {
+ union {
union {
struct xfrm_algo alg;
struct xfrm_algo_aead aead;
struct xfrm_algo_auth auth;
} u;
- char buf[XFRM_ALGO_KEY_BUF_SIZE];
+ struct {
+ unsigned char __offset_to_FAM[offsetof(struct
xfrm_algo_auth, alg_key)];
+ char buf[XFRM_ALGO_KEY_BUF_SIZE];
+ };
} alg = {};
size_t alen, elen, clen, aelen;
unsigned short type;
--
2.52.0
