linux-kernel - Re: [Intel-wired-lan] [PATCH v3] net: ethernet: fix uninitialized pointers with free attribute

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Message-ID: <aRtlYIZ2XOQKMGd_@stanley.mountain>
Date: Mon, 17 Nov 2025 21:11:44 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Alexander Lobakin <aleksander.lobakin@...el.com>
Cc: Ally Heev <allyheev@...il.com>,
	Tony Nguyen <anthony.l.nguyen@...el.com>,
	Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
	Aleksandr Loktionov <aleksandr.loktionov@...el.com>,
	intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org
Subject: Re: [Intel-wired-lan] [PATCH v3] net: ethernet: fix uninitialized
 pointers with free attribute

On Mon, Nov 17, 2025 at 03:37:30PM +0100, Alexander Lobakin wrote:
> From: Dan Carpenter <dan.carpenter@...aro.org>
> Date: Mon, 17 Nov 2025 16:11:32 +0300
> 
> > On Thu, Nov 06, 2025 at 03:07:26PM +0100, Alexander Lobakin wrote:
> >>> diff --git a/drivers/net/ethernet/intel/ice/ice_flow.c b/drivers/net/ethernet/intel/ice/ice_flow.c
> >>> index 6d5c939dc8a515c252cd2b77d155b69fa264ee92..3590dacf3ee57879b3809d715e40bb290e40c4aa 100644
> >>> --- a/drivers/net/ethernet/intel/ice/ice_flow.c
> >>> +++ b/drivers/net/ethernet/intel/ice/ice_flow.c
> >>> @@ -1573,12 +1573,13 @@ ice_flow_set_parser_prof(struct ice_hw *hw, u16 dest_vsi, u16 fdir_vsi,
> >>>  			 struct ice_parser_profile *prof, enum ice_block blk)
> >>>  {
> >>>  	u64 id = find_first_bit(prof->ptypes, ICE_FLOW_PTYPE_MAX);
> >>> -	struct ice_flow_prof_params *params __free(kfree);
> >>>  	u8 fv_words = hw->blk[blk].es.fvw;
> >>>  	int status;
> >>>  	int i, idx;
> >>>  
> >>> -	params = kzalloc(sizeof(*params), GFP_KERNEL);
> >>> +	struct ice_flow_prof_params *params __free(kfree) =
> >>> +		kzalloc(sizeof(*params), GFP_KERNEL);
> >>
> >> Please don't do it that way. It's not C++ with RAII and
> >> declare-where-you-use.
> >> Just leave the variable declarations where they are, but initialize them
> >> with `= NULL`.
> >>
> >> Variable declarations must be in one block and sorted from the longest
> >> to the shortest.
> >>
> > 
> > These days, with __free the trend is to say yes this is RAII and we
> > should declare it where you use it.  I personally don't have a strong
> 
> Sorta, but we can't "declare it where you use it" since we don't allow
> declaration-after-statement in the kernel.

That changed when we merged cleanup.h.  It is allowed now.  I still don't
like to declare variables anywhere unless it's a __free() variable and I
think almost everyone else agrees.  The only subsystem which I know that
completely moved to declaring variables willy-nilly was bcachefs.

regards,
dan carpenter