From nobody Wed Apr 1 12:32:54 2026 Received: from mxout70.expurgate.net (mxout70.expurgate.net [194.37.255.70]) (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 36D413CCFA9; Tue, 31 Mar 2026 07:43:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=194.37.255.70 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774943028; cv=none; b=mIAVA3MUTShjB4EiRmkPXhEBayFBs3PLY0wDF/Ff8ZjQzx8+k7V+tRhtsYsOqeHwYSSVG6rgLpjnkNVzsu3Ht+EgUF0HgjmDlSKiIpHnlT+7BEr3/Z7p3CGex0jsdCUbGnTc8Lx/2ZItkCvJxUIVyJsz0/ry2ph5J0XGOUGEoPU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774943028; c=relaxed/simple; bh=OdWsXOSpKx2KIVeAFa5xlYv3FnOYDsT/6PebGCuKocA=; h=From:Date:Subject:MIME-Version:Content-Type:Message-ID:References: In-Reply-To:To:Cc; b=kvfqPIJhi48hkzzno6VSTvdtPL2rovDjiUN+6h160/ZGhNbwxy94VeqIFOyWAsQEZyyADna386WAP2dT4/47He857F6+jLijesBk0lnl9vX+fyDIJIenjl/HOpHTXHDQuwuo6G8o1cW/bjfIGO+gFuLgydAF+NESF5iXcsbkdBY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=dev.tdt.de; spf=pass smtp.mailfrom=dev.tdt.de; dkim=temperror (0-bit key) header.d=dev.tdt.de header.i=@dev.tdt.de header.b=QfWikLGY; arc=none smtp.client-ip=194.37.255.70 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=dev.tdt.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=dev.tdt.de Authentication-Results: smtp.subspace.kernel.org; dkim=temperror (0-bit key) header.d=dev.tdt.de header.i=@dev.tdt.de header.b="QfWikLGY" Received: from [194.37.255.9] (helo=mxout.expurgate.net) by relay.expurgate.net with smtp (Exim 4.92) (envelope-from ) id 1w7Tl6-00FWkB-62; Tue, 31 Mar 2026 09:43:32 +0200 Received: from [195.243.126.94] (helo=securemail.tdt.de) by relay.expurgate.net with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1w7Tl4-006L8s-V4; Tue, 31 Mar 2026 09:43:31 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dev.tdt.de; s=z1-selector1; t=1774943010; bh=RoA2ct3WGvm4MFq2PE1vvrax7TpOpLDv7PngWSXsJPI=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=QfWikLGYlZjty08nrUgN0MWu8fyHfsBw950JpsJFArDkr3ZFVXVQ6fzH76fazc3YV QcH3+op8j0xiVK+eLkiFm/L3X6c58ipcrgL4TSIxnNVqA1zKaOGjX2FXyQcl5fq8Si blLyKkA5JLiBXn3TI+NM6888/Q8rewa1qZmjpfd9U230B0lGhc4gDftAcZcz4TbrHt gPcdC9u0Kr4rM8FmtvazwPnibxKgwBRzA8a2c+oPHW31XRmyyZCNofx29lwMUikiLQ y+/in/SN4QQgW6suar8ZPZyJlF/Lxrs77y8GQVne0qPE9SFIwJ7XgBYZF8mAWjPfuy ee/njllylUzfg== Received: from securemail.tdt.de (localhost [127.0.0.1]) by securemail.tdt.de (Postfix) with ESMTP id 62A0D240042; Tue, 31 Mar 2026 09:43:30 +0200 (CEST) Received: from mail.dev.tdt.de (unknown [10.2.4.42]) by securemail.tdt.de (Postfix) with ESMTP id 4A744240040; Tue, 31 Mar 2026 09:43:30 +0200 (CEST) Received: from [127.0.1.1] (unknown [10.2.3.19]) by mail.dev.tdt.de (Postfix) with ESMTPSA id 2FE8821989; Tue, 31 Mar 2026 09:43:30 +0200 (CEST) From: Martin Schiller Date: Tue, 31 Mar 2026 09:43:17 +0200 Subject: [PATCH net v4 1/2] net/x25: Fix potential double free of skb Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-ID: <20260331-x25_fraglen-v4-1-3e69f18464b4@dev.tdt.de> References: <20260331-x25_fraglen-v4-0-3e69f18464b4@dev.tdt.de> In-Reply-To: <20260331-x25_fraglen-v4-0-3e69f18464b4@dev.tdt.de> To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman Cc: Yiming Qian , linux-x25@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, security@kernel.org, Martin Schiller X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1774943009; l=1460; i=ms@dev.tdt.de; s=20260220; h=from:subject:message-id; bh=OdWsXOSpKx2KIVeAFa5xlYv3FnOYDsT/6PebGCuKocA=; b=e51TX5V2EIvzzl0DONlvncVMtdme6hep7B3EFNgU2CRWaZyCC/OM1WniHet2gNgW/Blw8tV2J +XP26y0Nmn7BQv50uI5nEO5dSLEaVE/osiPCfmEmtJY+7eHF8y8v15w X-Developer-Key: i=ms@dev.tdt.de; a=ed25519; pk=MAojd7D5IafMnqCYSFC7hY/u/jppX58CLIEhsEsSOYE= X-purgate-type: clean X-purgate-ID: 151534::1774943011-43C75BD0-9040426B/0/0 X-purgate: clean When alloc_skb fails in x25_queue_rx_frame it calls kfree_skb(skb) at line 48 and returns 1 (error). This error propagates back through the call chain: x25_queue_rx_frame returns 1 | v x25_state3_machine receives the return value 1 and takes the else branch at line 278, setting queued=3D0 and returning 0 | v x25_process_rx_frame returns queued=3D0 | v x25_backlog_rcv at line 452 sees queued=3D0 and calls kfree_skb(skb) again This would free the same skb twice. Looking at x25_backlog_rcv: net/x25/x25_in.c:x25_backlog_rcv() { ... queued =3D x25_process_rx_frame(sk, skb); ... if (!queued) kfree_skb(skb); } Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Martin Schiller --- net/x25/x25_in.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/net/x25/x25_in.c b/net/x25/x25_in.c index b981a4828d08c2e6676749a06035910eab01e6cd..0dbc73efab1cbd4d98fa77d7a72= a2b665203511b 100644 --- a/net/x25/x25_in.c +++ b/net/x25/x25_in.c @@ -44,10 +44,9 @@ static int x25_queue_rx_frame(struct sock *sk, struct sk= _buff *skb, int more) if (x25->fraglen > 0) { /* End of fragment */ int len =3D x25->fraglen + skb->len; =20 - if ((skbn =3D alloc_skb(len, GFP_ATOMIC)) =3D=3D NULL){ - kfree_skb(skb); + skbn =3D alloc_skb(len, GFP_ATOMIC); + if (!skbn) return 1; - } =20 skb_queue_tail(&x25->fragment_queue, skb); =20 --=20 2.47.3 From nobody Wed Apr 1 12:32:54 2026 Received: from mxout70.expurgate.net (mxout70.expurgate.net [194.37.255.70]) (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 36C7E3C8709; Tue, 31 Mar 2026 07:43:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=194.37.255.70 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774943027; cv=none; b=qzavV+V8E3jSKTH0RMAm25R3DrQEcfM245yp9087EGEfmRLL+ALKC1QSFoHeuNp1YF8nm38bwMLFGFU7xGV4Q+xjADED9IdNj3y8dGN5EvW+Yqdsr1YetKAF63rwif3Was3RCg1ItPjDMn1swaZcT0t7U9iYqT7MhS8myQz1LWI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774943027; c=relaxed/simple; bh=6xZwfUqOa8r+6op3B/IZvVXNg5HjxqI8HhsS8OBhfQA=; h=From:Date:Subject:MIME-Version:Content-Type:Message-ID:References: In-Reply-To:To:Cc; b=ITbMKzLKusmUdNu7i6nPqF5+j33LMCIWwykj0mi2rJZqGDXxGkt5JAY/STlYKW5HEQInSmsopm59RGY+zHfor/ja8bY+TpqHrFMnigy/LdGcfgnN1pi8KrSKhZaQYG+GIWzl41ztWfFDFv+zMgdrHpnLx9r2USnpos+1IB0aGvw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=dev.tdt.de; spf=pass smtp.mailfrom=dev.tdt.de; dkim=temperror (0-bit key) header.d=dev.tdt.de header.i=@dev.tdt.de header.b=NqFOb71+; arc=none smtp.client-ip=194.37.255.70 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=dev.tdt.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=dev.tdt.de Authentication-Results: smtp.subspace.kernel.org; dkim=temperror (0-bit key) header.d=dev.tdt.de header.i=@dev.tdt.de header.b="NqFOb71+" Received: from [194.37.255.9] (helo=mxout.expurgate.net) by relay.expurgate.net with smtp (Exim 4.92) (envelope-from ) id 1w7Tl6-00FWkA-5i; Tue, 31 Mar 2026 09:43:32 +0200 Received: from [195.243.126.94] (helo=securemail.tdt.de) by relay.expurgate.net with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1w7Tl5-00GjaX-2Y; Tue, 31 Mar 2026 09:43:31 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dev.tdt.de; s=z1-selector1; t=1774943010; bh=pauIbvWEvYDpHnmH5QLgiqWyOK2Mnf6AySmHb4La+Qw=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=NqFOb71+fFym7EVuCvt4M9NtwiAtKVK0yomgPBKMg32aZJKsPm3SPuiZPekA9PbX4 4HwTGj+zjhEV0mj0k2w/zFVhtp2GtbetpUG3amAKWd09Xn/+NnADTk4fl1So9MMST8 Lg9U1J6S15Ut5LaGXU5SlCJq8aG3Nb666NE3MtdZmRpJpxt9R9ME7kFgb88o2KLP/V K3HI/SBctn+OWEmncwBnzj+mcGluLDO/bWSt9W3eGoHOpzPC6skF6zye3RSgwIH5Tw 44eILyLDM0wf/vMZLQzRYxaImrQwoWnMntKJEB/x82/jbT8l8hQRvfnUA8A1NEiqmE dhKbAJtxn6U/A== Received: from securemail.tdt.de (localhost [127.0.0.1]) by securemail.tdt.de (Postfix) with ESMTP id 7A2C1240036; Tue, 31 Mar 2026 09:43:30 +0200 (CEST) Received: from mail.dev.tdt.de (unknown [10.2.4.42]) by securemail.tdt.de (Postfix) with ESMTP id 653DD240045; Tue, 31 Mar 2026 09:43:30 +0200 (CEST) Received: from [127.0.1.1] (unknown [10.2.3.19]) by mail.dev.tdt.de (Postfix) with ESMTPSA id 492DE20BF0; Tue, 31 Mar 2026 09:43:30 +0200 (CEST) From: Martin Schiller Date: Tue, 31 Mar 2026 09:43:18 +0200 Subject: [PATCH net v4 2/2] net/x25: Fix overflow when accumulating packets Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-ID: <20260331-x25_fraglen-v4-2-3e69f18464b4@dev.tdt.de> References: <20260331-x25_fraglen-v4-0-3e69f18464b4@dev.tdt.de> In-Reply-To: <20260331-x25_fraglen-v4-0-3e69f18464b4@dev.tdt.de> To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman Cc: Yiming Qian , linux-x25@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, security@kernel.org, Martin Schiller X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1774943009; l=1413; i=ms@dev.tdt.de; s=20260220; h=from:subject:message-id; bh=6xZwfUqOa8r+6op3B/IZvVXNg5HjxqI8HhsS8OBhfQA=; b=dhSZ7ZqbyLyM3u1rCYg53A/vD2dImU2miS7SQ3GP/sDhR8VKpdayKVwO/TDL3SZpqhhz+xhRO StwfYOMCnfiB4N4DQO1kVrDTsV0yM8AoxZT+YrF9D42L1MbQcjYItMW X-Developer-Key: i=ms@dev.tdt.de; a=ed25519; pk=MAojd7D5IafMnqCYSFC7hY/u/jppX58CLIEhsEsSOYE= X-purgate-ID: 151534::1774943011-41C71BD0-3D48CDD2/0/0 X-purgate-type: clean X-purgate: clean Add a check to ensure that `x25_sock.fraglen` does not overflow. The `fraglen` also needs to be resetted when purging `fragment_queue` in `x25_clear_queues()`. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Suggested-by: Yiming Qian Signed-off-by: Martin Schiller --- net/x25/x25_in.c | 4 ++++ net/x25/x25_subr.c | 1 + 2 files changed, 5 insertions(+) diff --git a/net/x25/x25_in.c b/net/x25/x25_in.c index 0dbc73efab1cbd4d98fa77d7a72a2b665203511b..e47ebd8acd21bff8d8fa1f5f481= 63145e9ac00f2 100644 --- a/net/x25/x25_in.c +++ b/net/x25/x25_in.c @@ -34,6 +34,10 @@ static int x25_queue_rx_frame(struct sock *sk, struct sk= _buff *skb, int more) struct sk_buff *skbo, *skbn =3D skb; struct x25_sock *x25 =3D x25_sk(sk); =20 + /* make sure we don't overflow */ + if (x25->fraglen + skb->len > USHRT_MAX) + return 1; + if (more) { x25->fraglen +=3D skb->len; skb_queue_tail(&x25->fragment_queue, skb); diff --git a/net/x25/x25_subr.c b/net/x25/x25_subr.c index 0285aaa1e93c17233748d38eef6d8b5c6059b67a..159708d9ad20cb2e6db24ead67d= af1e9d6258f64 100644 --- a/net/x25/x25_subr.c +++ b/net/x25/x25_subr.c @@ -40,6 +40,7 @@ void x25_clear_queues(struct sock *sk) skb_queue_purge(&x25->interrupt_in_queue); skb_queue_purge(&x25->interrupt_out_queue); skb_queue_purge(&x25->fragment_queue); + x25->fraglen =3D 0; } =20 =20 --=20 2.47.3