From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794564013; b=f3tTfGnmrXLfnggYgxmNZbgrEb0ix4PZ/bwZ7AZ5QOM6i0QDvAOk0dTEWTxek85NW9lN 3hFYV+ERZxiu2lle25XWEf8b34xAB/lJ7dg1kjH19k5Gx0dkSwmSf7p/CPliVwbXb6nEd gKc/4WTLNRbPiA1S2NXiJU7yn6AmHAvRkXqXFXH3daeQLJ9AY0BZnsLw2KyQypDdLfzDk ZCULXvWXNl0uFV+4g01SWJgh11vBXfMmGKmIXJE8TlUFS2A3wEIoL1Iw7mXlx2HMRIZxU KzmlPbfr0ioQw1chZKH5hGEi5IM9QTx6XS2XXtSOZRG6v0B4JnOu/ipWIBHY2ha6s9g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794564013; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=CZEQVZ6TVB8PXZyirm0oWvsQKQ+yV93wdSIBjZmPOVw=; b=g7qzc+yTROi725US3HFRyDcq2IsgmyrGKRKgvXT/PnjCuUzxCH8vub0jEtyoeSdkUada 3qwyCnCUpzO7GLX2qWgRXv4mUjqbkSCRCtf2+Hdxj+j2hZCF+PbMFmilSN5rDu4hQ/Yaf i23OMG4xsdZOyyYpr6kwAgvLqHeYCU3ZWj1rMy+aL2/EHWshUa+bzHy3sAs6THau9xOFw Rz8vKBpmtNA7AfHUN1LDd/7tjTY3VgugR+MYnEYJW8HkP2JZFWolV4Syc8drU8b0a2x3h Wc2g8bGPaGeWH04Fr9opaBmRR4JM8MuP+fKCxwCpzBJlxa0KdkqvxJWkONrqVeMdgRA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ioh3c7+L; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E1232606A337; Fri, 13 Nov 2026 10:00:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ioh3c7+L Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6CA301F000C4; Fri, 13 Nov 2026 10:00:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794564012; bh=CZEQVZ6TVB8PXZyirm0oWvsQKQ+yV93wdSIBjZmPOVw=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=ioh3c7+Li4hBvBjUiWmNiOBUipdlGq9BrKY1Gllg/1pwHe4dGrEqLu5Eib4iKE9vs UA9832q26rizKLXxFqb3g3RKIQUGWCCTjt+/s+xFwcTjDEEg3KR9dCESBg3O3OPw6R C6ADhMfinEJvPopECOflU3BqH+WfjYGOqM3GKZ9Mb39gFdGTLUx+dYJljEcRcYp2hn 5f8AW0yrwbSj1r832w81nTXfJfKBtgE24MDxl5w1cLa3mmbQUJYbPgU+Jo1lrJ18m2 ghFcegLfOjleLF6tlNqaFnaN7YTQgvJceIomLGKtoE2Y6u2WKM19qo40jfINrRbA3E ynOw0pUK1sf8g== Date: Fri, 13 Nov 2026 10:00:07 +0000 From: Simon Horman To: Xia Yan Cc: netdev@vger.kernel.org, oe-linux-nfc@lists.linux.dev, David Heidelberg , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Thierry Escande , Samuel Ortiz , Samuel Ortiz , linux-kernel@vger.kernel.org, yana06070@163.com Subject: Re: [PATCH net-next] NFC: digital: fix target leak after Type 1 Tag discovery Message-ID: <20261113100007.GI18859@horms.kernel.org> References: <20261109031832.37642-1-yanxia@cmss.chinamobile.com> X-Mailing-List: oe-linux-nfc@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261109031832.37642-1-yanxia@cmss.chinamobile.com> On Mon, Nov 09, 2026 at 03:18:32AM +0000, Xia Yan wrote: > digital_in_recv_sens_res() allocates a target for an NFC-A response. > For a Type 1 Tag, it calls digital_target_found() synchronously. > nfc_targets_found() copies the target into dev->targets. > > On success, rc is zero and the callback skips kfree(target). > The original allocation is lost when the callback returns. > Each completed Type 1 Tag discovery leaks one struct nfc_target. > > Free the target after digital_target_found() returns. Clear the pointer > to avoid freeing it again on the error path. Keep the target for other > tag types, whose discovery continues asynchronously. > > Found during a code review of NFC-A target ownership. > > Fixes: 2c66daecc409 ("NFC Digital: Add NFC-A technology support") > Signed-off-by: Xia Yan > --- > net/nfc/digital_technology.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/net/nfc/digital_technology.c b/net/nfc/digital_technology.c > index ae6487c10a25..2d52e390cc67 100644 > --- a/net/nfc/digital_technology.c > +++ b/net/nfc/digital_technology.c > @@ -510,10 +510,13 @@ static void digital_in_recv_sens_res(struct nfc_digital_dev *ddev, void *arg, > goto exit; > } > > - if (DIGITAL_SENS_RES_IS_T1T(target->sens_res)) > + if (DIGITAL_SENS_RES_IS_T1T(target->sens_res)) { > rc = digital_target_found(ddev, target, NFC_PROTO_JEWEL); > - else > + kfree(target); > + target = NULL; > + } else { > rc = digital_in_send_sdd_req(ddev, target); > + } > > exit: > dev_kfree_skb(resp); Thanks Yan, I agree this is a bug and that you patch correctly addresses it. However, I wonder if it would be cleaner to confine cleanup to the exit path, centralising the kfree logic. Something like this (compile tested only!): diff --git a/net/nfc/digital_technology.c b/net/nfc/digital_technology.c index ae6487c10a25..94880172f016 100644 --- a/net/nfc/digital_technology.c +++ b/net/nfc/digital_technology.c @@ -483,6 +483,7 @@ static void digital_in_recv_sens_res(struct nfc_digital_dev *ddev, void *arg, struct sk_buff *resp) { struct nfc_target *target = NULL; + bool res_is_t1t = false; int rc; if (IS_ERR(resp)) { @@ -510,7 +511,8 @@ static void digital_in_recv_sens_res(struct nfc_digital_dev *ddev, void *arg, goto exit; } - if (DIGITAL_SENS_RES_IS_T1T(target->sens_res)) + res_is_t1t = DIGITAL_SENS_RES_IS_T1T(target->sens_res); + if (res_is_t1t) rc = digital_target_found(ddev, target, NFC_PROTO_JEWEL); else rc = digital_in_send_sdd_req(ddev, target); @@ -518,10 +520,11 @@ static void digital_in_recv_sens_res(struct nfc_digital_dev *ddev, void *arg, exit: dev_kfree_skb(resp); - if (rc) { + if (rc || res_is_t1t) kfree(target); + + if (rc) digital_poll_next_tech(ddev); - } } int digital_in_send_sens_req(struct nfc_digital_dev *ddev, u8 rf_tech)