From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f194.google.com (mail-pg1-f194.google.com [209.85.215.194]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 09DE82C0285 for ; Wed, 25 Feb 2026 03:38:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.194 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771990734; cv=none; b=gnXg7EzWgip7qYixS818eOW4ytjbYZVtJX5Mp43Z4XTcyiwdA3mCnwlS8GqVs9Y423NICp4+TJTfnDPFRbDjQg1qA5Rr3vWd1a9XXa0107QcxoO27Ybekw179cEV591PGumiA7zQALVHp7JbNBe5i6EKRM69+Q9h+o0Y0/umIIo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771990734; c=relaxed/simple; bh=UzebxA6/a7fg3sjOiWp/u7lzb1dFODtxX1sVJYsce3s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aJyJANEfOj3ERIX4EMHCpNt8vcifWbxp885PUoShEiZieauQHMYawIFqelgTPxirvujw1xFVuWYprJrOAjZCv+3gvF/fOjNrgG85c1RKbpqrwwm2hG6upkzxJebQIxi09oC9TJp/FcghAMdv5S04g+VqEmgnL0yR2eMMYzizLcI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=k6S3wZ3H; arc=none smtp.client-ip=209.85.215.194 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="k6S3wZ3H" Received: by mail-pg1-f194.google.com with SMTP id 41be03b00d2f7-c6e3e4e7388so2079228a12.1 for ; Tue, 24 Feb 2026 19:38:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1771990731; x=1772595531; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=JqCX+A7B/xYK3O+/EJk4ZtsIswe0wWdZp+sEMdt10Pc=; b=k6S3wZ3H77CAxACFcz+o72T6A6R+BsHZBrvPdcvF7tvFLxxp+fSNCau7O67NC9Ve95 1yKvbrnImEVYaubbGKPND4duldzGqHnxm9KJHzlnoaPc1634VPnoN5MkBwWc1rjhEXBF 57aZyVNEXB5s50xJupBvdv7xvBCPgtVJIpiQQXN5+aSZ8ImqM2ZkUJHpAZXx9vh64jqh e4rG+hBhdR19sJgWdhhjlnEHzM2SXDJn7s0HxAIJEqtt4y/VBnjYwMn6higD48rWGyJy Nqzntkgw2huX2R3OBlY4MY0CH1mZH0Nut+IuQiQ/ST74FB9wf3Jhi90VYK26O1sYJSdW 3R4Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1771990731; x=1772595531; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=JqCX+A7B/xYK3O+/EJk4ZtsIswe0wWdZp+sEMdt10Pc=; b=pD2YK7R08aR+FC4+fGvlQj8DlaZgV7HetuWJpxfAGe1A5uhohRuDubQzsLhvy9UmKV k+/zun9ZVTrUTO2tWaszanMczKJNaxwR4LMSfGi0Cl3D0QyIUcvAjXaGweM2RsNQCogm kybntVhC2KyOipnEnFRhPZ6Ll0lRu8tVuPyo8OxSJM5cPvNnHiNpA7Frd3Tf1kg3MnBV 5/GL8ITIlFBV+TFzpTT/1hKAEDhfH7o7QQQ13nJ9HNr0VWHKGLyoc4dZvlpBSrsuFTxt tIMDPFJpm/bM4l+wFU6MUBorUScqXPDHxHU+gae8pHaGhPTwVaqXPNU4PbHOSSLkdYIe i7Wg== X-Forwarded-Encrypted: i=1; AJvYcCVJ/dePO2DpQAnu1XH/Ji8TYrl0UmIR70go0GHG2v7g9UIg7jZViRClY3W406CFJsjujpyskg55rM7Y8o8=@vger.kernel.org X-Gm-Message-State: AOJu0YxWyw2x/s2p3JyfOx8jRHdEHpOzpeZ/nAgH3hVEvZJ/zYX86Zm2 TuoFtNGdSMdpGKWjV2Oobvz6J5S3ohbqcoFUgk2vVazWDi+tRRH+qhNq X-Gm-Gg: ATEYQzxCQFJS4rsTj0SwxrGVQMQJwkGuG7Iu5vedh+k/FYOasZExsF3BKOYdbre4bLV OMsLTe2YwXnm7W4r5ywoP8Xh4++XI5DvUOTL3NaaSzesMSVkc4nUyr5j26jsRO3WvcrZF5frhyw eOwIwLcEFTu93G8D1mnrzkXOqABOnF17+58p6XcZcYdC6UHDW6PAQlB8HmUu9XjmBCMS1FK5L0i KRDFbrzHjEziXKGOtNmrra/vF+UIouPbSVpazbwcDOFQanOdc9yfmdWCbnkpWl7sn6s5/LlXq0Y FlhkGQWXoUoXyhBef9OEcq+2GQX6J2ZBX+umHMWvAf1oXCyChHYprooE4eQEwpLH9a/0TV8l2MJ etgebZ6jxxg3j+C3RgZz8BRWea0nSqQ/wa38LE4WtcJ6WGuOXICHInTJ6A40VioBNaVDoxetvWl 4uXbFD+34KKcM4T3Ao+Mwy9JyjyBl21ZwLJZKZaxssqXR58GtIyKhZFZtJX9nhH0veb2xQSMrom Ds6NCHp X-Received: by 2002:a17:90a:c887:b0:356:23be:7ecb with SMTP id 98e67ed59e1d1-358ae808fb4mr11595307a91.12.1771990731279; Tue, 24 Feb 2026 19:38:51 -0800 (PST) Received: from localhost.localdomain ([138.199.21.245]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-359018838b2sm1161746a91.5.2026.02.24.19.38.47 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 24 Feb 2026 19:38:50 -0800 (PST) From: Eric-Terminal To: Dominique Martinet , Eric Van Hensbergen , Latchesar Ionkov , "David S . Miller" , Jakub Kicinski Cc: v9fs@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Nikolay Aleksandrov , bridge@lists.linux.dev, Anna Schumaker , Chuck Lever , linux-nfs@vger.kernel.org, Yufan Chen Subject: [PATCH v2 1/4] 9p/trans_xen: make cleanup idempotent after dataring alloc errors Date: Wed, 25 Feb 2026 11:38:37 +0800 Message-ID: <20260225033840.33000-2-ericterminal@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260225033840.33000-1-ericterminal@gmail.com> References: <20260225010853.15916-1-ericterminal@gmail.com> <20260225033840.33000-1-ericterminal@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3411; i=ericterminal@gmail.com; h=from:subject; bh=Gu0MyqKlwATaZLTHkAVxYELyEu7nRq9nuCfzTHc2Ad8=; b=owGbwMvMwCXWM/dCzeS3H+sZT6slMWTOy5NTm/gzgiOsN2hHx4cJz7fzhr19LZHb++7ufoVZo snTztnZdZSyMIhxMciKKbLc/b9vbq7XrTnXuQ/nwsxhZQIZwsDFKQATuWbAyHDC3ICJlbVC0rBZ fRMn18uDx4MObX75UfXy+stNxZIpL/4y/BXwOLHVb3ZcItMd+/SAj2IK0WHehYmHLjAYvrrHufu tEDsA X-Developer-Key: i=ericterminal@gmail.com; a=openpgp; fpr=DDFFBE9D6D4ADA9CD70BC36D8C9DD07C93EDF17F Content-Transfer-Encoding: 8bit From: Yufan Chen xen_9pfs_front_alloc_dataring() tears down resources on failure but leaves ring fields stale. If xen_9pfs_front_init() later jumps to the common error path, xen_9pfs_front_free() may touch the same resources again, causing duplicate/invalid gnttab_end_foreign_access() calls and potentially dereferencing a freed intf pointer. Initialize dataring sentinels before allocation, gate teardown on those sentinels, and clear ref/intf/data/irq immediately after each release. This keeps cleanup idempotent for partially initialized rings and prevents repeated teardown during init failure handling. Signed-off-by: Yufan Chen --- net/9p/trans_xen.c | 51 +++++++++++++++++++++++++++++++++------------- 1 file changed, 37 insertions(+), 14 deletions(-) diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c index 47af5a10e..85b9ebfaa 100644 --- a/net/9p/trans_xen.c +++ b/net/9p/trans_xen.c @@ -283,25 +283,33 @@ static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv) cancel_work_sync(&ring->work); - if (!priv->rings[i].intf) + if (!ring->intf) break; - if (priv->rings[i].irq > 0) - unbind_from_irqhandler(priv->rings[i].irq, ring); - if (priv->rings[i].data.in) { - for (j = 0; - j < (1 << priv->rings[i].intf->ring_order); + if (ring->irq >= 0) { + unbind_from_irqhandler(ring->irq, ring); + ring->irq = -1; + } + if (ring->data.in) { + for (j = 0; j < (1 << ring->intf->ring_order); j++) { grant_ref_t ref; - ref = priv->rings[i].intf->ref[j]; + ref = ring->intf->ref[j]; gnttab_end_foreign_access(ref, NULL); + ring->intf->ref[j] = INVALID_GRANT_REF; } - free_pages_exact(priv->rings[i].data.in, - 1UL << (priv->rings[i].intf->ring_order + - XEN_PAGE_SHIFT)); + free_pages_exact(ring->data.in, + 1UL << (ring->intf->ring_order + + XEN_PAGE_SHIFT)); + ring->data.in = NULL; + ring->data.out = NULL; + } + if (ring->ref != INVALID_GRANT_REF) { + gnttab_end_foreign_access(ring->ref, NULL); + ring->ref = INVALID_GRANT_REF; } - gnttab_end_foreign_access(priv->rings[i].ref, NULL); - free_page((unsigned long)priv->rings[i].intf); + free_page((unsigned long)ring->intf); + ring->intf = NULL; } kfree(priv->rings); } @@ -334,6 +342,12 @@ static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev, int ret = -ENOMEM; void *bytes = NULL; + ring->intf = NULL; + ring->data.in = NULL; + ring->data.out = NULL; + ring->ref = INVALID_GRANT_REF; + ring->irq = -1; + init_waitqueue_head(&ring->wq); spin_lock_init(&ring->lock); INIT_WORK(&ring->work, p9_xen_response); @@ -379,9 +393,18 @@ static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev, for (i--; i >= 0; i--) gnttab_end_foreign_access(ring->intf->ref[i], NULL); free_pages_exact(bytes, 1UL << (order + XEN_PAGE_SHIFT)); + ring->data.in = NULL; + ring->data.out = NULL; + } + if (ring->ref != INVALID_GRANT_REF) { + gnttab_end_foreign_access(ring->ref, NULL); + ring->ref = INVALID_GRANT_REF; + } + if (ring->intf) { + free_page((unsigned long)ring->intf); + ring->intf = NULL; } - gnttab_end_foreign_access(ring->ref, NULL); - free_page((unsigned long)ring->intf); + ring->irq = -1; return ret; } -- 2.47.3