netdev - Re: [PATCH net 2/2] net: atm: fix /proc/net/atm/lec handling

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Message-ID: <20250618234338.GA2863787@electric-eye.fr.zoreil.com>
Date: Thu, 19 Jun 2025 01:43:38 +0200
From: Francois Romieu <romieu@...zoreil.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
        netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: [PATCH net 2/2] net: atm: fix /proc/net/atm/lec handling

Eric Dumazet <edumazet@...gle.com> :
> /proc/net/atm/lec must ensure safety against dev_lec[] changes.
> 
> It appears it had dev_put() calls without prior dev_hold(),
> leading to imbalance and UAF.
> 
> Fixes: da177e4c3f41 ("Linux-2.6.12-rc2")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> ---
>  net/atm/lec.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/net/atm/lec.c b/net/atm/lec.c
> index 1e1f3eb0e2ba3cc1caa52e49327cecb8d18250e7..afb8d3eb2185078eb994e70c67d581e6dd96a452 100644
> --- a/net/atm/lec.c
> +++ b/net/atm/lec.c

Acked-by: Francois Romieu <romieu@...zoreil.com> # Minor atm contributor

While moving proc handling code from net/atm/proc.c to net/atm/lec.c after
seq_file conversion back in september 2003, there was a misguided change
turning:

dev = state->dev ? state->dev : atm_lane_ops->get_lec(state->itf);

into:

dev = state->dev ? state->dev : dev_lec[state->itf];

.get_lec included dev_hold. I didn't notice the change :/

-- 
Ueimor