From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 304D0431A48; Mon, 17 Aug 2026 13:18:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786972728; cv=none; b=lIFL3qjCAjd1hr2nDCLDKl69A1TGw9WahXVtxB0iWtd4W+NUH/c0yUqJ3fdxWiBaEOid/NS6MEEitWXJC26KD1NUhQVhrVPl3oNUccTKI4Oj5yI5ttyFHVCzkvcHD6gGgrtnlvBCL1tTnn0mIekvLPwy5FJTKywVrqUO9SPHjgc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786972728; c=relaxed/simple; bh=OWePMOmwdyShVhOmzWbcXXZUZcMzehJKIqCfmwdipOM=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=Lxz1vwpoQZPAld+spTRzsTzlrJLQ3XHQJUh+nryb/abzQ7cBpxiAXxGTubU0EQ61u7zHV7lLxPNWBt24xebsvvGaDPq4RBv2VlwHi88iUlod3NwIVc0wWMt/k9TDIZ9FlHqOcpMnew9gar1u1GzhDTlcyDpU6xF4Js1FZMeJYPw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fSHC72zT; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fSHC72zT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F5C31F00A3D; Mon, 17 Aug 2026 13:18:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786972727; bh=P4mcfXtxvAc8wd7J9tSmqaTRpcpUcJTv24dB9nbPHvk=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=fSHC72zTjNjqE+VQ83++VEfiyEIWGwu1SaOplEOIBSINmjqXwqPhUhrqEMZmrz014 u5x9FtG3Cw8moHzLw13RMikTeqP89XZRR7d7NrAOS9GQztGKV2ip4XhtAoK13s3cGh A7V8X1c+rx89bg4tOlYSRXqZF97MoBQkzy0csoRImIDl2yJxX0vCkB+sReIhI+Boti npjA/xkkOi8xCTHLbAKMpp7O7u/+RVJ5mBxRUmu9Z692dxRheDSiQRLC+wwQ+gm+/9 HkS8XtoEBDeTbXnNAlIdOXMg6R3bF5hkA7bunSrl1aunZV++tDdcXb6W8yswEmbY+b TLgvBTNVHbS1g== Message-ID: Subject: Re: [PATCH] lockd: fix NULL pointer dereference in nlmclnt_locks_release_private From: Jeff Layton To: Ran Hongyun , cel@kernel.org, trondmy@kernel.org, anna@kernel.org, viro@zeniv.linux.org.uk Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, chengzhihao1@huawei.com, yangerkun@huawei.com, yi.zhang@huawei.com Date: Mon, 17 Aug 2026 09:18:44 -0400 In-Reply-To: <20260817060820.963195-1-ranhongyun1@huawei.com> References: <20260817060820.963195-1-ranhongyun1@huawei.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Mon, 2026-08-17 at 14:08 +0800, Ran Hongyun wrote: > nlmclnt_locks_init_private() unconditionally sets fl->fl_ops even when > nlmclnt_find_lockowner() returns NULL due to allocation failure. When > locks_release_private() later sees a non-NULL fl_ops, it calls > fl_release_private, which dereferences fl->fl_u.nfs_fl.owner. >=20 > nlmclnt_proc() > nlmclnt_locks_init_private <----set fl->fl_ops unconditionally > if (!fl->fl_u.nfs_fl.owner) <----forget to clear fl->fl_ops >=20 > locks_release_private() > if (fl->fl_ops) <----fl->fl_ops is not NULL but owner is NULL > fl->fl_ops->fl_release_private() > nlmclnt_locks_release_private() <----NULL ptr dereference >=20 > Fix this by clearing fl_ops when nlmclnt_find_lockowner() fails in > nlmclnt_proc(), so that locks_release_private() skips the > fl_release_private call path. >=20 > Fixes: bf8848918d75 ("lockd: handle lockowner allocation failure in nlmcl= nt_proc()") > Signed-off-by: Ran Hongyun > --- > fs/lockd/clntproc.c | 1 + > 1 file changed, 1 insertion(+) >=20 > diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c > index f06faf577cea..4b54481fecd5 100644 > --- a/fs/lockd/clntproc.c > +++ b/fs/lockd/clntproc.c > @@ -176,6 +176,7 @@ int nlmclnt_proc(struct nlm_host *host, int cmd, stru= ct file_lock *fl, void *dat > if (!fl->fl_u.nfs_fl.owner) { > /* lockowner allocation has failed */ > nlmclnt_release_call(call); > + fl->fl_ops =3D NULL; > return -ENOMEM; > } > /* Set up the argument struct */ The fix looks correct, but I don't like the way that the initialization and cleanup is spread across multiple functions. I think it would be better to just get rid of nlmclnt_locks_init_private() altogether and open code what it does in the single caller (nlmclnt_proc()). Then you could just not initialize fl_ops if nlmclnt_find_lockowner() fails. There's also another preexisting bug here. If the lockowner allocation fails, this function also leaks the references taken in nlmclnt_alloc_call(). Want to spin up a v2 that fixes all of this? --=20 Jeff Layton