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Date: Mon, 15 Jun 2026 13:08:00 +0100
From: Simon Horman <horms@kernel.org>
To: NeKon69 <nobodqwe@gmail.com>
Cc: anthony.l.nguyen@intel.com, przemyslaw.kitszel@intel.com,
	andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com,
	kuba@kernel.org, pabeni@redhat.com, victor.raj@intel.com,
	intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] ice: Fix use-after-scope in
 ice_sched_add_nodes_to_layer()
Message-ID: <20260615120800.GA757061@horms.kernel.org>
References: <20260613101440.80190-1-nobodqwe@gmail.com>
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In-Reply-To: <20260613101440.80190-1-nobodqwe@gmail.com>

On Sat, Jun 13, 2026 at 01:14:40PM +0300, NeKon69 wrote:
> Commit 7fb09a737536 ("ice: Modify recursive way of adding nodes")
> changed ice_sched_add_nodes_to_layer() from recursive control flow to an
> iterative loop.
> 
> Inside the loop, first_teid_ptr may be set to the address of a
> block-local variable:
> 
> 	u32 temp;
> 	...
> 	if (num_added)
> 		first_teid_ptr = &temp;
> 
> On the next loop iteration, first_teid_ptr may be passed to
> ice_sched_add_nodes_to_hw_layer(), after temp from the previous
> iteration has gone out of scope.
> 
> Move temp outside the loop so the pointer remains valid for the lifetime
> of ice_sched_add_nodes_to_layer().
> 
> This was found by Clang with LifetimeSafety enabled while testing C
> language support on a Linux allmodconfig build.
> 
> Fixes: 7fb09a737536 ("ice: Modify recursive way of adding nodes")
> Link: https://github.com/llvm/llvm-project/pull/203270
> Signed-off-by: NeKon69 <nobodqwe@gmail.com>

I agree that this patch is correct.

However, I do wonder if it would be cleaner to allow
passing NULL as the first_node_teid argument of
ice_sched_add_nodes_to_hw_layer()

...