linux-kernel - Re: [PATCH net] netlink: Fix off-by-one error in netlink_proto

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Message-ID: <CANn89iJCshHRan=w_YMp7bEeBadOjNS7PU392q2K4qNTRtz=Ow@mail.gmail.com>
Date: Mon, 28 Oct 2024 16:20:20 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: Jinjie Ruan <ruanjinjie@...wei.com>
Cc: davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com, horms@...nel.org, 
	kuniyu@...zon.com, a.kovaleva@...ro.com, lirongqing@...du.com, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] netlink: Fix off-by-one error in netlink_proto_init()

On Mon, Oct 28, 2024 at 9:05 AM Jinjie Ruan <ruanjinjie@...wei.com> wrote:
>
> In the error path of netlink_proto_init(), frees the already allocated
> bucket table for new hash tables in a loop, but the loop condition
> terminates when the index reaches zero, which fails to free the first
> bucket table at index zero.
>
> Check for >= 0 so that nl_table[0].hash is freed as well.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
> ---
>  net/netlink/af_netlink.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
> index 0a9287fadb47..9601b85dda95 100644
> --- a/net/netlink/af_netlink.c
> +++ b/net/netlink/af_netlink.c
> @@ -2936,7 +2936,7 @@ static int __init netlink_proto_init(void)
>         for (i = 0; i < MAX_LINKS; i++) {
>                 if (rhashtable_init(&nl_table[i].hash,
>                                     &netlink_rhashtable_params) < 0) {
> -                       while (--i > 0)
> +                       while (--i >= 0)
>                                 rhashtable_destroy(&nl_table[i].hash);
>                         kfree(nl_table);
>                         goto panic;
> --

Note that the host is going to panic, many other pieces of memory are
left behind.

A Fixes: tag seems unnecessary.