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wireguard: netlink: avoid variable-sized memcpy on sockaddr

Hangbin Liu requested to merge liuhangbin/centos-stream-9:bz2135317_wg into main

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2135317 Upstream Status: net.git commit 26c013108c12

commit 26c013108c12b94bc023bf19198a4300596c98b1 Author: Jason A. Donenfeld Jason@zx2c4.com Date: Fri Sep 16 15:37:40 2022 +0100

wireguard: netlink: avoid variable-sized memcpy on sockaddr

Doing a variable-sized memcpy is slower, and the compiler isn't smart
enough to turn this into a constant-size assignment.

Further, Kees' latest fortified memcpy will actually bark, because the
destination pointer is type sockaddr, not explicitly sockaddr_in or
sockaddr_in6, so it thinks there's an overflow:

    memcpy: detected field-spanning write (size 28) of single field
    "&endpoint.addr" at drivers/net/wireguard/netlink.c:446 (size 16)

Fix this by just assigning by using explicit casts for each checked
case.

Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reported-by: syzbot+a448cda4dba2dac50de5@syzkaller.appspotmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Hangbin Liu haliu@redhat.com

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