From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lamorak.hansenpartnership.com (lamorak.hansenpartnership.com [198.37.111.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 00FEC221269; Wed, 5 Nov 2025 15:32:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.37.111.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762356743; cv=none; b=H7ygj+pMR0wFCS2FpQFZrbR9LpzK1jUzajLzWQjuPo91XDW/UAWZzfby4OSk0MyZHBu6/nuLEKxLvpVjo/yQl7qlxbi494XLGcV1yGYIOREv10R3ZOLqD91I5hur90SI8tYVs1/3FGZNNCqdq+nV8g89GlIf4g2x8ohKrYcuFn8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762356743; c=relaxed/simple; bh=F6jCVB5FUTfR1/fbnGPmSEAnI5kBmVbJxWWuGwAZSaE=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=fAK6BgxiBTeBsiADzCcVmB4RzkJvErzlOLWotsK/PbuJ16mnD02P6+Qy+7UXWM5By5toJ6KdTj0rwd9+ajlxvOFvOlvN210l2pFq7OvmVJKwv8Th83bsieUnLowGTV3SdVPyMKPl0CTMimALDwTJBpik5mhjQn8sCxO4S58y5SA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=HansenPartnership.com; spf=pass smtp.mailfrom=HansenPartnership.com; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b=KRpKtWwq; arc=none smtp.client-ip=198.37.111.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="KRpKtWwq" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1762356740; bh=F6jCVB5FUTfR1/fbnGPmSEAnI5kBmVbJxWWuGwAZSaE=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=KRpKtWwqeI+uhoAcDEQfN/z+YVbcMPVDKNflF/Zkh9BgoPkSsq7TQRj/SF74pxIO3 pOvo7loVvjsDz/GetDBA9v49h+0tY+bxd9lKq4NnIxfdZsohTpJGhcVX16tQYORYyf jO7XcrPYarxLpuEo8B9dprrZnnOTiL9CaBO2W5w8= Received: from lingrow.int.hansenpartnership.com (unknown [IPv6:2601:5c4:4302:c21::a774]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lamorak.hansenpartnership.com (Postfix) with ESMTPSA id 8DF1F1C02BB; Wed, 05 Nov 2025 10:32:20 -0500 (EST) Message-ID: <407aed0ff7be4fdcafebd09e58e25496b6b4fec0.camel@HansenPartnership.com> Subject: Re: [PATCH] scsi: fix uninitialized pointers with free attr From: James Bottomley To: Dan Carpenter Cc: Ally Heev , "Martin K. Petersen" , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 05 Nov 2025 10:32:19 -0500 In-Reply-To: References: <20251105-aheev-uninitialized-free-attr-scsi-v1-1-d28435a0a7ea@gmail.com> <6d199d062b16abfbf083750820d7a39cb2ebf144.camel@HansenPartnership.com> Autocrypt: addr=James.Bottomley@HansenPartnership.com; prefer-encrypt=mutual; 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 8mT2Eh9SkH+YVOmaKsajgZgrBxA7fWmGoxXswEVxJIFj3vW7yNc0C5HaUdYa5iGOMs4kg2ht4s7yy7NRQuh7BifWjo6BQ6k4S1H+6axZucxhSV1L6zN9d+lr3Xo/vy1unzA== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.3 Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2025-11-05 at 17:46 +0300, Dan Carpenter wrote: > On Wed, Nov 05, 2025 at 09:21:45AM -0500, James Bottomley wrote: > > On Wed, 2025-11-05 at 19:44 +0530, Ally Heev wrote: > > > Uninitialized pointers with `__free` attribute can cause > > > undefined > > > behaviour as the memory assigned(randomly) to the pointer is > > > freed > > > automatically when the pointer goes out of scope > > >=20 > > > scsi doesn't have any bugs related to this as of now, but > > > it is better to initialize and assign pointers with `__free` attr > > > in one statement to ensure proper scope-based cleanup > > >=20 > > > Reported-by: Dan Carpenter > > > Closes: > > > https://lore.kernel.org/all/aPiG_F5EBQUjZqsl@stanley.mountain/ > > > Signed-off-by: Ally Heev > > > --- > > > =C2=A0drivers/scsi/scsi_debug.c | 4 ++-- > > > =C2=A01 file changed, 2 insertions(+), 2 deletions(-) > > >=20 > > > diff --git a/drivers/scsi/scsi_debug.c > > > b/drivers/scsi/scsi_debug.c > > > index > > > b2ab97be5db3d43d5a5647968623b8db72448379..89b36d65926bdd15c0ae93a > > > 6bd2 > > > ea968e25c0e74 100644 > > > --- a/drivers/scsi/scsi_debug.c > > > +++ b/drivers/scsi/scsi_debug.c > > > @@ -2961,11 +2961,11 @@ static int resp_mode_sense(struct > > > scsi_cmnd > > > *scp, > > > =C2=A0 int target_dev_id; > > > =C2=A0 int target =3D scp->device->id; > > > =C2=A0 unsigned char *ap; > > > - unsigned char *arr __free(kfree); > > > =C2=A0 unsigned char *cmd =3D scp->cmnd; > > > =C2=A0 bool dbd, llbaa, msense_6, is_disk, is_zbc, is_tape; > > > =C2=A0 > > > - arr =3D kzalloc(SDEBUG_MAX_MSENSE_SZ, GFP_ATOMIC); > > > + unsigned char *arr __free(kfree) =3D > > > kzalloc(SDEBUG_MAX_MSENSE_SZ, GFP_ATOMIC); > > > + > >=20 > > Moving variable assignments inside code makes it way harder to > > read. Given that compilers will eventually detect if we do a return > > before initialization, can't you have smatch do the same rather > > than trying to force something like this? >=20 > This isn't a Smatch thing, it's a change to checkpatch. >=20 > (Smatch does work as you describe). So why are we bothering with something like this in checkpatch if we can detect the true problem condition and we expect compilers to catch up? Encouraging people to write code like the above isn't in anyone's best interest. Regards, James