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Fri, 10 Jul 2026 16:20:31 +0000 (GMT) Received: from [9.124.217.113] (unknown [9.124.217.113]) by smtpav02.wdc07v.mail.ibm.com (Postfix) with ESMTP; Fri, 10 Jul 2026 16:20:30 +0000 (GMT) Message-ID: Date: Fri, 10 Jul 2026 21:50:28 +0530 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] net/af_iucv: fix NULL deref in afiucv_hs_callback_syn() To: "Jagielski, Jedrzej" , "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" References: <20260709191732.124092-1-hidayath@linux.ibm.com> Content-Language: en-GB From: Hidayathulla Khan I In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=VebH+lp9 c=1 sm=1 tr=0 ts=6a511bd9 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=VwQbUJbxAAAA:8 a=EGRZ104ItT1sqjb4XsEA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: lBZ6gJ55hd8rUgtCX85dNJW8K3ouhM-U X-Proofpoint-ORIG-GUID: B3MyERg9-DGZMCU4Xf_rkrHGdIZGgevS X-Proofpoint-Spam-Info: AW1haW4tMjYwNzEwMDE2MyBTYWx0ZWRfX5xaq1VDW1+bK p2w9+6fnw01R/AkOyuRuV+gS4yO+p/buEpAOO+73llI27oUECk4DhDdYvmshGckDZgTNKLrOsOf V1cwhDNesxbUFzy1VwtvRvFTRBK8OFI= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzEwMDE2MyBTYWx0ZWRfX/MYWQdmsHPNm fMe4AknV+6p/DEtKHkDYBH2mulFkHtmXK6CissaCCc1LjDwVHnGA3X8zpRX17jliwKiu1wCDsmV IcntUFxANKCghDSGsXSwoelzwJaiC/Ut554KHMuAQBOTbiME9wfR3JkuPKpwd6uQA99STS6DROY OLwfDCPxJfyQybTFwJageN5x0CJ8f9kiVQkdUKgj/xdOjo/WOkHtW6SrioHZaxPgDt9slpdS7YU vqaCK7mhgDsjKFBZCDMjX6kOWvxs1qoWQDEqDfeWV+lWvoi61RJgk4mk/WVgXOaVo8Hp/S6aaqO ijLhDGxyq5fuXoYZX5ss+uUG5qoBDsyKvzR3bVs9xLZpN6h13Yt2yZM3qoispxnwnmJElcBB6LA JbFJzYWAQmj3+xoUa84CWl2G0dThomJ05yTnqJhn8SbNbol6sXrBVH2UceYmZ2qmm6IVG1YrQjd P4B7/qElAvPRL2g58kQ== 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=2026-07-10_04,2026-07-10_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 suspectscore=0 clxscore=1011 malwarescore=0 impostorscore=0 phishscore=0 lowpriorityscore=0 adultscore=0 spamscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607100163 On 10/07/26 3:04 pm, Jagielski, Jedrzej wrote: > From: Hidayath Khan > Sent: Thursday, July 9, 2026 9:18 PM > >> 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) > Hi Hidayath > > why not to move this check into iucv_sock_kill()? > would prevent from potential similar issues in the future Hi Jedrzej, Every other call to iucv_sock_kill() passes a non-NULL socket by construction. If iucv_sock_kill() silently accepted NULL, a future caller wrongly passing NULL would go unnoticed instead of being caught. > >> + iucv_sock_kill(nsk); >> bh_unlock_sock(sk); >> goto out; >> } >> >> base-commit: 262b2eac463d880a664cf92af1107b4f9d84ad37 >> -- >> 2.52.0 > >