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Fri, 6 Nov 2020 12:50:10 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 6 Nov 2020 12:50:10 +0000 (GMT) From: Julian Wiedmann To: David Miller , Jakub Kicinski Cc: linux-netdev , linux-s390 , Heiko Carstens , Karsten Graul , Julian Wiedmann , Ursula Braun Subject: [PATCH net 1/2] net/af_iucv: fix null pointer dereference on shutdown Date: Fri, 6 Nov 2020 13:50:07 +0100 Message-Id: <20201106125008.36478-2-jwi@linux.ibm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201106125008.36478-1-jwi@linux.ibm.com> References: <20201106125008.36478-1-jwi@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312, 18.0.737 definitions=2020-11-06_04:2020-11-05,2020-11-06 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 mlxlogscore=999 clxscore=1015 priorityscore=1501 bulkscore=0 lowpriorityscore=0 phishscore=0 malwarescore=0 spamscore=0 suspectscore=0 mlxscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011060088 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Ursula Braun syzbot reported the following KASAN finding: BUG: KASAN: nullptr-dereference in iucv_send_ctrl+0x390/0x3f0 net/iucv/af_iucv.c:385 Read of size 2 at addr 000000000000021e by task syz-executor907/519 CPU: 0 PID: 519 Comm: syz-executor907 Not tainted 5.9.0-syzkaller-07043-gbcf9877ad213 #0 Hardware name: IBM 3906 M04 701 (KVM/Linux) Call Trace: [<00000000c576af60>] unwind_start arch/s390/include/asm/unwind.h:65 [inline] [<00000000c576af60>] show_stack+0x180/0x228 arch/s390/kernel/dumpstack.c:135 [<00000000c9dcd1f8>] __dump_stack lib/dump_stack.c:77 [inline] [<00000000c9dcd1f8>] dump_stack+0x268/0x2f0 lib/dump_stack.c:118 [<00000000c5fed016>] print_address_description.constprop.0+0x5e/0x218 mm/kasan/report.c:383 [<00000000c5fec82a>] __kasan_report mm/kasan/report.c:517 [inline] [<00000000c5fec82a>] kasan_report+0x11a/0x168 mm/kasan/report.c:534 [<00000000c98b5b60>] iucv_send_ctrl+0x390/0x3f0 net/iucv/af_iucv.c:385 [<00000000c98b6262>] iucv_sock_shutdown+0x44a/0x4c0 net/iucv/af_iucv.c:1457 [<00000000c89d3a54>] __sys_shutdown+0x12c/0x1c8 net/socket.c:2204 [<00000000c89d3b70>] __do_sys_shutdown net/socket.c:2212 [inline] [<00000000c89d3b70>] __s390x_sys_shutdown+0x38/0x48 net/socket.c:2210 [<00000000c9e36eac>] system_call+0xe0/0x28c arch/s390/kernel/entry.S:415 There is nothing to shutdown if a connection has never been established. Besides that iucv->hs_dev is not yet initialized if a socket is in IUCV_OPEN state and iucv->path is not yet initialized if socket is in IUCV_BOUND state. So, just skip the shutdown calls for a socket in these states. Fixes: eac3731bd04c ("s390: Add AF_IUCV socket support") Fixes: 82492a355fac ("af_iucv: add shutdown for HS transport") Reviewed-by: Vasily Gorbik Signed-off-by: Ursula Braun Signed-off-by: Julian Wiedmann --- 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 d80572074667..047238f01ba6 100644 --- a/net/iucv/af_iucv.c +++ b/net/iucv/af_iucv.c @@ -1434,7 +1434,8 @@ static int iucv_sock_shutdown(struct socket *sock, int how) break; } - if (how == SEND_SHUTDOWN || how == SHUTDOWN_MASK) { + if ((how == SEND_SHUTDOWN || how == SHUTDOWN_MASK) && + sk->sk_state == IUCV_CONNECTED) { if (iucv->transport == AF_IUCV_TRANS_IUCV) { txmsg.class = 0; txmsg.tag = 0;