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 73557209F43 for ; Wed, 16 Apr 2025 14:15:16 +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=1744812916; cv=none; b=RBQZuhGYcM7sv/py4gaLvWbrIX8W7ZfIdyruU6N0vZmPsDR37VEkPB9K1RCNyeZxczFOkBp6DaSfmnYAFmr13j+rjz2W1mozdg9D72JpaaA5ClOZdV+cTJrIGQKB79a282siIkeoH88/KikzlGSfLqNvmiQtJawkKEbdSCooujI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744812916; c=relaxed/simple; bh=jJWO0oOU63yGDzNEjXIRweHXl22cStdecqN4eJBSbp0=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=oPTFykKmxmZvKnjPa5wFC4g12z9ev96dormasAyA/CEz0E0GZ/0Q2erPvrJcHeotSsHAmeao40XP5M59tAZfpGqgXwce2o4vv1elwVz6CvRWyhApcfTATe3+/Q+PvT5WgQNIjG3wVJANp4QY+F2QOWqe00xzAaS0nfOtlWqlZrU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=bGUyQ4hB; 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="bGUyQ4hB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E1D20C4CEE2; Wed, 16 Apr 2025 14:15:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1744812916; bh=jJWO0oOU63yGDzNEjXIRweHXl22cStdecqN4eJBSbp0=; h=From:To:Cc:Subject:Date:Reply-to:From; b=bGUyQ4hBekjDRAbd43syl16jCJk78nZgX3rec2w0A6JOsPeHk8788RHlgsJs6DpQn pEQOqAiOR+OtdbAhI4sYM58jiaMOwKpvLjhckZN1NOQ5N6pR5bsvue2J2JjJdYGtyF MJJobqaOaQM/+pTHxFgtnIhTJmUXMxrMjjXdrAqU= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2025-22058: udp: Fix memory accounting leak. Date: Wed, 16 Apr 2025 16:12:29 +0200 Message-ID: <2025041606-CVE-2025-22058-045a@gregkh> X-Mailer: git-send-email 2.49.0 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=5968; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=jJWO0oOU63yGDzNEjXIRweHXl22cStdecqN4eJBSbp0=; b=owGbwMvMwCRo6H6F97bub03G02pJDOn/d207WpOyVolrQsyyzaZanNLFTfoGC/uuXGtdpO0W+ ODPpdsJHbEsDIJMDLJiiixftvEc3V9xSNHL0PY0zBxWJpAhDFycAjCRb48ZFkwydNy9f5uFefLx S7oTODtdw1dsnskwv+RitzLT4gU6pecmF35dYVAR076zBQA= 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: udp: Fix memory accounting leak. Matt Dowling reported a weird UDP memory usage issue. Under normal operation, the UDP memory usage reported in /proc/net/sockstat remains close to zero. However, it occasionally spiked to 524,288 pages and never dropped. Moreover, the value doubled when the application was terminated. Finally, it caused intermittent packet drops. We can reproduce the issue with the script below [0]: 1. /proc/net/sockstat reports 0 pages # cat /proc/net/sockstat | grep UDP: UDP: inuse 1 mem 0 2. Run the script till the report reaches 524,288 # python3 test.py & sleep 5 # cat /proc/net/sockstat | grep UDP: UDP: inuse 3 mem 524288 <-- (INT_MAX + 1) >> PAGE_SHIFT 3. Kill the socket and confirm the number never drops # pkill python3 && sleep 5 # cat /proc/net/sockstat | grep UDP: UDP: inuse 1 mem 524288 4. (necessary since v6.0) Trigger proto_memory_pcpu_drain() # python3 test.py & sleep 1 && pkill python3 5. The number doubles # cat /proc/net/sockstat | grep UDP: UDP: inuse 1 mem 1048577 The application set INT_MAX to SO_RCVBUF, which triggered an integer overflow in udp_rmem_release(). When a socket is close()d, udp_destruct_common() purges its receive queue and sums up skb->truesize in the queue. This total is calculated and stored in a local unsigned integer variable. The total size is then passed to udp_rmem_release() to adjust memory accounting. However, because the function takes a signed integer argument, the total size can wrap around, causing an overflow. Then, the released amount is calculated as follows: 1) Add size to sk->sk_forward_alloc. 2) Round down sk->sk_forward_alloc to the nearest lower multiple of PAGE_SIZE and assign it to amount. 3) Subtract amount from sk->sk_forward_alloc. 4) Pass amount >> PAGE_SHIFT to __sk_mem_reduce_allocated(). When the issue occurred, the total in udp_destruct_common() was 2147484480 (INT_MAX + 833), which was cast to -2147482816 in udp_rmem_release(). At 1) sk->sk_forward_alloc is changed from 3264 to -2147479552, and 2) sets -2147479552 to amount. 3) reverts the wraparound, so we don't see a warning in inet_sock_destruct(). However, udp_memory_allocated ends up doubling at 4). Since commit 3cd3399dd7a8 ("net: implement per-cpu reserves for memory_allocated"), memory usage no longer doubles immediately after a socket is close()d because __sk_mem_reduce_allocated() caches the amount in udp_memory_per_cpu_fw_alloc. However, the next time a UDP socket receives a packet, the subtraction takes effect, causing UDP memory usage to double. This issue makes further memory allocation fail once the socket's sk->sk_rmem_alloc exceeds net.ipv4.udp_rmem_min, resulting in packet drops. To prevent this issue, let's use unsigned int for the calculation and call sk_forward_alloc_add() only once for the small delta. Note that first_packet_length() also potentially has the same problem. [0]: from socket import * SO_RCVBUFFORCE = 33 INT_MAX = (2 ** 31) - 1 s = socket(AF_INET, SOCK_DGRAM) s.bind(('', 0)) s.setsockopt(SOL_SOCKET, SO_RCVBUFFORCE, INT_MAX) c = socket(AF_INET, SOCK_DGRAM) c.connect(s.getsockname()) data = b'a' * 100 while True: c.send(data) The Linux kernel CVE team has assigned CVE-2025-22058 to this issue. Affected and fixed versions =========================== Issue introduced in 4.10 with commit f970bd9e3a06f06df8d8ecf1f8ad2c8615cc17eb and fixed in 6.1.134 with commit 9122fec396950cc866137af7154b1d0d989be52e Issue introduced in 4.10 with commit f970bd9e3a06f06df8d8ecf1f8ad2c8615cc17eb and fixed in 6.6.87 with commit aeef6456692c6f11ae53d278df64f1316a2a405a Issue introduced in 4.10 with commit f970bd9e3a06f06df8d8ecf1f8ad2c8615cc17eb and fixed in 6.12.23 with commit a116b271bf3cb72c8155b6b7f39083c1b80dcd00 Issue introduced in 4.10 with commit f970bd9e3a06f06df8d8ecf1f8ad2c8615cc17eb and fixed in 6.13.11 with commit c4bac6c398118fba79e32b1cd01db22dbfe29fbf Issue introduced in 4.10 with commit f970bd9e3a06f06df8d8ecf1f8ad2c8615cc17eb and fixed in 6.14.2 with commit 3836029448e76c1e6f77cc5fe0adc09b018b5fa8 Issue introduced in 4.10 with commit f970bd9e3a06f06df8d8ecf1f8ad2c8615cc17eb and fixed in 6.15-rc1 with commit df207de9d9e7a4d92f8567e2c539d9c8c12fd99d 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-2025-22058 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/ipv4/udp.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/9122fec396950cc866137af7154b1d0d989be52e https://git.kernel.org/stable/c/aeef6456692c6f11ae53d278df64f1316a2a405a https://git.kernel.org/stable/c/a116b271bf3cb72c8155b6b7f39083c1b80dcd00 https://git.kernel.org/stable/c/c4bac6c398118fba79e32b1cd01db22dbfe29fbf https://git.kernel.org/stable/c/3836029448e76c1e6f77cc5fe0adc09b018b5fa8 https://git.kernel.org/stable/c/df207de9d9e7a4d92f8567e2c539d9c8c12fd99d