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088f35ab9f
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.
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Ankit Khushwaha <ankitkhushwaha.linux@gmail.com>
Link: https://patch.msgid.link/20260109152201.15668-1-ankitkhushwaha.linux@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>