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Thu, 20 Aug 2026 07:46:43 +0000 (GMT) Received: from t83lp68.lnxne.boe (unknown [9.87.84.240]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 20 Aug 2026 07:46:43 +0000 (GMT) From: Hidayath Khan To: alibuda@linux.alibaba.com, dust.li@linux.alibaba.com, sidraya@linux.ibm.com, mjambigi@linux.ibm.com, andrew+netdev@lunn.ch Cc: tonylu@linux.alibaba.com, guwen@linux.alibaba.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, pasic@linux.ibm.com, hidayath@linux.ibm.com, linux-s390@vger.kernel.org, netdev@vger.kernel.org, linux-rdma@vger.kernel.org Subject: [PATCH net v2 0/2] net/smc: fix use-after-free in smc_rx_pipe_buf_release() Date: Thu, 20 Aug 2026 09:46:40 +0200 Message-ID: <20260820074642.966856-1-hidayath@linux.ibm.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=MthiLWae c=1 sm=1 tr=0 ts=6a86b0e9 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=64RyPHVN2Ejl6unEET8A:9 X-Proofpoint-ORIG-GUID: g8t_QR1qI84c4kMOMydn4USVw36XOY2n X-Proofpoint-GUID: sBc4Tu9rnp9_mrI60RJxK9yG8GD206DN X-Proofpoint-Spam-Info: AW1haW4tMjYwODIwMDA1MyBTYWx0ZWRfX+HPrW+s3wbqQ vKpOQV1kB/kqt+WFSQuLkaO1tqMrGbAoVOqfX9faSBIlVhXHfZJkZBbPAaF0Q9BxeA77l0Fj6YC BH2IAJfJNICoSaEzD2rSU++ceMgIuAk= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODIwMDA1MyBTYWx0ZWRfX4TWSpOuBIOsy iYczbYvswUGK3MwMea+Yb0NoTSgnaAPhL/ONxebMMOE67e/bdkL9jre778lUfzReSjqGlIC20tY xqaU0zLXQZDnlQA4VbSxiuvVU+gg8whJarHJJDmVB9CqSi2qljKTHcAHDUEJC1WMKo5x05IsXby mNOJA+o82T4JME2NsK5/y6npwRaBlTmtfMec/GnF4GOqCyujS6TYqOJ1yTNzDD1vubSR3t4s0TU Q4uRQEhha0tjjVxJNJkRyiP3EQCBEcbKQ5yAFWvyHVqEf792/lSSeUzAYJKsfeTuuXjoLCJU+ad LzmXpTnfsMTt3b2+sSGkIQDXiQTpgusO+r05x0q/xO6KwJSjzKHraPaT3ukQDsztdPAucUaIY87 3iK1smF46Mlm+YbtPQU7srFYxGG6ZFeMTuhkeR0nURpP0uiZAC6PXbLmkHcm8T74IQc2r5IA1zy /4CNJd/u3iMLF3iQrCA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-19_06,2026-08-19_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 impostorscore=0 bulkscore=0 phishscore=0 clxscore=1015 spamscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608200053 smc_rx_pipe_buf_release() tests sk_state before taking the socket lock and then dereferences conn->rmb_desc and conn->lgr. A concurrent close runs smc_conn_free() in between, which releases those structures. On the is_reg_err path smcr_buf_unuse() frees the descriptor outright, so this is a use-after-free. Patch 2/2 fixes this by taking the socket lock first and testing conn->freed instead. smc_conn_free() sets that flag before releasing anything, under the same lock, so the two paths exclude each other. Patch 1/2 is a prerequisite. conn->freed shares a byte with killed and out_of_sync as single-bit bitfields. out_of_sync is written from the receive tasklet without the socket lock, so a concurrent store to freed from process context can be lost in the read-modify-write. Patch 1/2 gives each flag its own byte so stores do not interfere. Hidayath Khan (2): net/smc: stop killed, freed and out_of_sync sharing a byte net/smc: fix use-after-free in smc_rx_pipe_buf_release() net/smc/smc.h | 6 +++--- net/smc/smc_rx.c | 11 +++++------ 2 files changed, 8 insertions(+), 9 deletions(-) --- v2: - Patch 1/2 is new. It is a prerequisite for 2/2. - Patch 2/2 replaces the conn->rmb_desc = NULL approach from v1 with a conn->freed check. The NULL store exposed smc_cdc_msg_recv_action() and the sock_diag dump to NULL dereferences on paths that do not take the socket lock. -- 2.52.0