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Thu, 9 Jul 2026 19:17:33 +0000 (GMT) From: Hidayath Khan To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: horms@kernel.org, linux-s390@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, wintera@linux.ibm.com, twinkler@linux.ibm.com, heiko.carstens@de.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, hidayath@linux.ibm.com Subject: [PATCH net] net/af_iucv: fix NULL deref in afiucv_hs_callback_syn() Date: Thu, 9 Jul 2026 21:17:32 +0200 Message-ID: <20260709191732.124092-1-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-Proofpoint-GUID: NXn5DVpO6ueY8MIWNudF1jYm5CA_wQxP X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzA5MDE4NiBTYWx0ZWRfX29HCDHg2IVxC o9gaWQhb5U4TuDx85U9OuTp84RQMSW9fQLZNPS1XrsTFmrmay2CUye8134/cnt3pa8srk0Qtgpp lTSrtewQ6XpYdq4kVbjXgQA4ubAkVcGQ50Sgn7YaSeO9Hg3o5fMovj6HEUrHu3wycyx8wjAecrX eIUlBphAGP9r+d90Ej0lChmnwkdJjHOgfKoL2iPJ8ddn+iiXc/yhJRLmXWbfLlmeGmDu0xFlmQY Kt6ePMkgEnYVHVu6V3eYd6uEUJ3nEQ/xGvZXZPV80b3+vomrGs+yfQBUv2iRtpWBMlssQGv5ubL 87f+IfNmCk6vWrQxH3kucm7U6tmz1/3bnBRuqwLpiGa2BksVzsXuymQBbYytAhiwhOTkFOhLYff ynNxl/vE29LRj0qvrcMzcVITTdlWIuN4mbny395v+IOjwx9No+vsqXgHhgKCQqCsJQbE4m+NwIH wEirXL7taFFn/Yr/xPg== X-Proofpoint-ORIG-GUID: t6Rv0bnmOeQZ-znRcVDm_Wu4v1o-AOMv X-Authority-Analysis: v=2.4 cv=FqQ1OWrq c=1 sm=1 tr=0 ts=6a4ff3d4 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=lZ-7vaNzbJThIC_oh1kA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzA5MDE4NiBTYWx0ZWRfXwsuPbVwRX4Jl ZWFaDxco1XGBqQCSDnBAmp/YBLjHLhxqKv+FAYRbIb14XXulYuMW71JjoUYPPsB2szZDn38L8ka S2BK+kBqzEJdH5kYSs+Ok1T+7aLBnYs= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-09_04,2026-07-09_04,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 impostorscore=0 clxscore=1015 malwarescore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 suspectscore=0 spamscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607090186 afiucv_hs_callback_syn() allocates the child socket with GFP_ATOMIC. If the allocation fails, nsk is NULL. The connection-refused path is entered when the listen state check fails, the accept backlog is full, or nsk is NULL. The code unconditionally calls iucv_sock_kill(nsk) in that path. iucv_sock_kill() does not accept a NULL socket pointer and immediately dereferences sk via sock_flag(sk, SOCK_ZAPPED). When nsk is NULL, calling iucv_sock_kill(nsk) results in a NULL pointer dereference. Only call iucv_sock_kill() when a child socket was successfully allocated. Fixes: 3881ac441f64 ("af_iucv: add HiperSockets transport") Cc: stable@vger.kernel.org Reviewed-by: Alexandra Winter Signed-off-by: Hidayath Khan --- net/iucv/af_iucv.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c index fed240b453bd..f5b1ec44b6ae 100644 --- a/net/iucv/af_iucv.c +++ b/net/iucv/af_iucv.c @@ -1872,7 +1872,8 @@ static int afiucv_hs_callback_syn(struct sock *sk, struct sk_buff *skb) afiucv_swap_src_dest(skb); trans_hdr->flags = AF_IUCV_FLAG_SYN | AF_IUCV_FLAG_FIN; err = dev_queue_xmit(skb); - iucv_sock_kill(nsk); + if (nsk) + iucv_sock_kill(nsk); bh_unlock_sock(sk); goto out; } base-commit: 262b2eac463d880a664cf92af1107b4f9d84ad37 -- 2.52.0