linux-kernel - Re: [PATCH 6.1.y v2] net/sched: act_mirred: don't override retval if we already lost the skb

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Message-ID: <2025042844-pavestone-fringe-1478@gregkh>
Date: Mon, 28 Apr 2025 13:46:03 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: jianqi.ren.cn@...driver.com
Cc: stable@...r.kernel.org, patches@...ts.linux.dev,
	linux-kernel@...r.kernel.org, jhs@...atatu.com,
	xiyou.wangcong@...il.com, jiri@...nulli.us, davem@...emloft.net,
	kuba@...nel.org, pabeni@...hat.com, netdev@...r.kernel.org,
	michal.swiatkowski@...ux.intel.com, zhe.he@...driver.com
Subject: Re: [PATCH 6.1.y v2] net/sched: act_mirred: don't override retval if
 we already lost the skb

On Mon, Apr 28, 2025 at 04:01:03PM +0800, jianqi.ren.cn@...driver.com wrote:
> From: Jakub Kicinski <kuba@...nel.org>
> 
> [ Upstream commit 166c2c8a6a4dc2e4ceba9e10cfe81c3e469e3210 ]
> 
> If we're redirecting the skb, and haven't called tcf_mirred_forward(),
> yet, we need to tell the core to drop the skb by setting the retcode
> to SHOT. If we have called tcf_mirred_forward(), however, the skb
> is out of our hands and returning SHOT will lead to UaF.
> 
> Move the retval override to the error path which actually need it.
> 
> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
> Fixes: e5cf1baf92cb ("act_mirred: use TC_ACT_REINSERT when possible")
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>
> Acked-by: Jamal Hadi Salim <jhs@...atatu.com>
> Signed-off-by: David S. Miller <davem@...emloft.net>
> [Minor conflict resolved due to code context change.]
> Signed-off-by: Jianqi Ren <jianqi.ren.cn@...driver.com>
> Signed-off-by: He Zhe <zhe.he@...driver.com>
> ---
> v2: Fix the following issue
> net/sched/act_mirred.c:265:6: error: variable 'is_redirect' is used
> uninitialized whenever 'if' condition is true
> found by the following tuxmake
> (https://lore.kernel.org/stable/CA+G9fYu+FEZ-3ye30Hk2sk1+LFsw7iO5AHueUa9H1Ub=JO-k2g@mail.gmail.com/)
> Verified the build test by cmd(tuxmake --runtime podman --target-arch arm
>  --toolchain clang-20 --kconfig allmodconfig LLVM=1 LLVM_IAS=1)

I see 2 "v2" patches here, both different, so I'm dropping both of them
:(