Re: [PATCH net-next v4] rust: net: netlink: validate attribute length before casting to `c_int`

On Wed Sep 23, 2026 at 9:05 PM JST, Sagar Taunk wrote:

`put()` trusted an unchecked `as` cast from `usize` to `c_int`.
When the length exceeds `i32::MAX` that cast wraps around to a
negative value.

This ultimately resulted in a kernel panic when the reinterpreted
value via `__nla_reserve()` and `skb_put()` became enormous.

Validate payload and header both fit together in a `u16`, rejecting
any payload that wouldn't leave room for `NLA_HDRLEN`.

Fixes: 5eaa5fbb6e6c ("rust: netlink: add raw netlink abstraction")
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Sagar Taunk <redacted>

FWIW,

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>