From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 BD120346FB0; Wed, 8 Apr 2026 18:43:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775673802; cv=none; b=IVPDnDMbFQWipMyFDzB9kgNgWa9HlyAkIKpbN6QdqfAaqPtc1HE3CI959JRKeZC1H0sKQCsIBfmVAkuqG/tCGvRX1yWZcgn6zg2tJ1j2Ei28kK76ewk/5RS2CJQNN0wWcOIKC0sAc16JtOdTLivWnfiFtuMWtSqBLOf4y0obSbc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775673802; c=relaxed/simple; bh=SWx/qjd0v/XEDTojjEibeEbRK2VAISZz+fQtd33WQnA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ju1FfMEIgSyabUZDm7fDoyMw4oorrmLuwJHCiGh79hytL+fyhMqaNJ7LK7Qb8fY+oRl6iQ9YgbpTNu/mkgsS5thJqMl4ZdssWW5VFbD/noaLXPrNsPeU7lpJxZudFiXDStG0yFEIh7lvZunQqDnlrI40cCBl1kYYhj2/oBhqrrA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xrWPRPng; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="xrWPRPng" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53E24C19421; Wed, 8 Apr 2026 18:43:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1775673802; bh=SWx/qjd0v/XEDTojjEibeEbRK2VAISZz+fQtd33WQnA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xrWPRPngGSrf69K1O+EyVHYXNfJLbIk3Fgu5jjBCxcz+O4f2Y0bbyYJLPCfpZKpfO YE6xAuRW6I+KBm5jW16o4rM1lmCeWd1g0dVLIjUzXXwWS2EjoOvH3JS2JewX5K/7S6 AbfQsZGx3KrlNcEnHc9MbV1bmGYxythtVzIjDZGY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Martin Schiller , Paolo Abeni , Sasha Levin Subject: [PATCH 6.12 095/242] net/x25: Fix potential double free of skb Date: Wed, 8 Apr 2026 20:02:15 +0200 Message-ID: <20260408175930.639332669@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260408175927.064985309@linuxfoundation.org> References: <20260408175927.064985309@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Martin Schiller [ Upstream commit d10a26aa4d072320530e6968ef945c8c575edf61 ] 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=0 and returning 0 | v x25_process_rx_frame returns queued=0 | v x25_backlog_rcv at line 452 sees queued=0 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 = x25_process_rx_frame(sk, skb); ... if (!queued) kfree_skb(skb); } Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Martin Schiller Link: https://patch.msgid.link/20260331-x25_fraglen-v4-1-3e69f18464b4@dev.tdt.de Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- 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 b981a4828d08c..0dbc73efab1cb 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 = x25->fraglen + skb->len; - if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){ - kfree_skb(skb); + skbn = alloc_skb(len, GFP_ATOMIC); + if (!skbn) return 1; - } skb_queue_tail(&x25->fragment_queue, skb); -- 2.53.0