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 6CA371A5B8A for ; Wed, 26 Feb 2025 01:58:09 +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=1740535089; cv=none; b=sW+pr1mSirsdjQQ4oqLBD+dVemk8D6X77mT6uZaJmy2wmB+6iO0JsiaQkOv75laABhQCFJZrf+oYTH4d5jt2fEhlNM5o36fMhoV3xyAxwcGsNdB3g9L8kgewjquhipIXHrD5ekrU6MiB4diHKBhYnGdx1MSqXuaP/ZMF2POevVQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740535089; c=relaxed/simple; bh=OVeUAKxUGjTa/uHr8D2sHSHqYLpMLWIsVA73mX3BO7o=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=gyP1IPDygp/S/+XSdeRZ/+DkxYnVdX6EnnaPh6j6YnRuFgEJ4xFhPRqX9LebFr5t5qjRmdmIGpwB1xYWeqv+bnZl2w1A1oTuzHGo1BpfKdI2JzCa1ziBGflGzg+q4+mrUJ6D/Wn9ExEi7Gi897BipAsZ7i33OUZR9IWz0UYQfqM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=WN1hw/H0; 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="WN1hw/H0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 42BF9C4CEDD; Wed, 26 Feb 2025 01:58:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1740535089; bh=OVeUAKxUGjTa/uHr8D2sHSHqYLpMLWIsVA73mX3BO7o=; h=From:To:Cc:Subject:Date:Reply-to:From; b=WN1hw/H08Rueepm1pr71s5wqWZ/0NK0TScbnGzRm7ehxkk0eToMTj0YEpI16tLbcJ zEtZQ55HAHMI4Sy0/HGWRoKEWXRsZjyr2ldtEor+46IrrcsvMCz50yNE7IUaTP+wj1 W1cYWdmyThbTLnYooey/EF6ErBgzELBN7dYhDy5k= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2022-49093: skbuff: fix coalescing for page_pool fragment recycling Date: Wed, 26 Feb 2025 02:54:58 +0100 Message-ID: <2025022659-CVE-2022-49093-0ccf@gregkh> X-Mailer: git-send-email 2.48.1 Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Reply-to: , X-Developer-Signature: v=1; a=openpgp-sha256; l=5432; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=OVeUAKxUGjTa/uHr8D2sHSHqYLpMLWIsVA73mX3BO7o=; b=owGbwMvMwCRo6H6F97bub03G02pJDOn7SsyDpbNWdZzZdipjG/fO6thVYpViR+WEFronn5oj4 cK7g+V/RywLgyATg6yYIsuXbTxH91ccUvQytD0NM4eVCWQIAxenAExkmS/DgknqF2YuT0nfUzvR 7jvz4ylBjstTTzDM4Ti2cn9dQFiFiJRiUL6Ga3WfjnoJAA== X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit Description =========== In the Linux kernel, the following vulnerability has been resolved: skbuff: fix coalescing for page_pool fragment recycling Fix a use-after-free when using page_pool with page fragments. We encountered this problem during normal RX in the hns3 driver: (1) Initially we have three descriptors in the RX queue. The first one allocates PAGE1 through page_pool, and the other two allocate one half of PAGE2 each. Page references look like this: RX_BD1 _______ PAGE1 RX_BD2 _______ PAGE2 RX_BD3 _________/ (2) Handle RX on the first descriptor. Allocate SKB1, eventually added to the receive queue by tcp_queue_rcv(). (3) Handle RX on the second descriptor. Allocate SKB2 and pass it to netif_receive_skb(): netif_receive_skb(SKB2) ip_rcv(SKB2) SKB3 = skb_clone(SKB2) SKB2 and SKB3 share a reference to PAGE2 through skb_shinfo()->dataref. The other ref to PAGE2 is still held by RX_BD3: SKB2 ---+- PAGE2 SKB3 __/ / RX_BD3 _________/ (3b) Now while handling TCP, coalesce SKB3 with SKB1: tcp_v4_rcv(SKB3) tcp_try_coalesce(to=SKB1, from=SKB3) // succeeds kfree_skb_partial(SKB3) skb_release_data(SKB3) // drops one dataref SKB1 _____ PAGE1 \____ SKB2 _____ PAGE2 / RX_BD3 _________/ In skb_try_coalesce(), __skb_frag_ref() takes a page reference to PAGE2, where it should instead have increased the page_pool frag reference, pp_frag_count. Without coalescing, when releasing both SKB2 and SKB3, a single reference to PAGE2 would be dropped. Now when releasing SKB1 and SKB2, two references to PAGE2 will be dropped, resulting in underflow. (3c) Drop SKB2: af_packet_rcv(SKB2) consume_skb(SKB2) skb_release_data(SKB2) // drops second dataref page_pool_return_skb_page(PAGE2) // drops one pp_frag_count SKB1 _____ PAGE1 \____ PAGE2 / RX_BD3 _________/ (4) Userspace calls recvmsg() Copies SKB1 and releases it. Since SKB3 was coalesced with SKB1, we release the SKB3 page as well: tcp_eat_recv_skb(SKB1) skb_release_data(SKB1) page_pool_return_skb_page(PAGE1) page_pool_return_skb_page(PAGE2) // drops second pp_frag_count (5) PAGE2 is freed, but the third RX descriptor was still using it! In our case this causes IOMMU faults, but it would silently corrupt memory if the IOMMU was disabled. Change the logic that checks whether pp_recycle SKBs can be coalesced. We still reject differing pp_recycle between 'from' and 'to' SKBs, but in order to avoid the situation described above, we also reject coalescing when both 'from' and 'to' are pp_recycled and 'from' is cloned. The new logic allows coalescing a cloned pp_recycle SKB into a page refcounted one, because in this case the release (4) will drop the right reference, the one taken by skb_try_coalesce(). The Linux kernel CVE team has assigned CVE-2022-49093 to this issue. Affected and fixed versions =========================== Issue introduced in 5.15 with commit 53e0961da1c7bbdabd1abebb20de403ec237ec09 and fixed in 5.15.34 with commit ba965e8605aee5387cecaa28fcf7ee9f61779a49 Issue introduced in 5.15 with commit 53e0961da1c7bbdabd1abebb20de403ec237ec09 and fixed in 5.16.20 with commit c4fa19615806a9a7e518c295b39175aa47a685ac Issue introduced in 5.15 with commit 53e0961da1c7bbdabd1abebb20de403ec237ec09 and fixed in 5.17.3 with commit 72bb856d16e883437023ff2ff77d0c498018728a Issue introduced in 5.15 with commit 53e0961da1c7bbdabd1abebb20de403ec237ec09 and fixed in 5.18 with commit 1effe8ca4e34c34cdd9318436a4232dcb582ebf4 Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2022-49093 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: net/core/skbuff.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/ba965e8605aee5387cecaa28fcf7ee9f61779a49 https://git.kernel.org/stable/c/c4fa19615806a9a7e518c295b39175aa47a685ac https://git.kernel.org/stable/c/72bb856d16e883437023ff2ff77d0c498018728a https://git.kernel.org/stable/c/1effe8ca4e34c34cdd9318436a4232dcb582ebf4