Subject: [syzbot] KMSAN: uninit-value in sctp_inq_pop (2)

From: syzbot <[email-masked]>
Date: Sat, 08 Jan 2022 00:00:25 -0800

Hello,

syzbot found the following issue on:

HEAD commit:    81c325bbf94e kmsan: hooks: do not check memory in kmsan_in..
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=15dad2c3b00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2d8b9a11641dc9aa
dashboard link: https://syzkaller.appspot.com/bug?extid=70a42f45e76bede082be
compiler:       clang version 14.0.0 (/usr/local/google/src/llvm-git-monorepo 2b554920f11c8b763cd9ed9003f4e19b919b8e1f), GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=173a7b0db00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14de2ffdb00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

netlink: 244 bytes leftover after parsing attributes in process `syz-executor678'.
=====================================================
BUG: KMSAN: uninit-value in sctp_inq_pop+0x15c8/0x18f0 net/sctp/inqueue.c:205
 sctp_inq_pop+0x15c8/0x18f0 net/sctp/inqueue.c:205
 sctp_assoc_bh_rcv+0x1fa/0xdd0 net/sctp/associola.c:1000
 sctp_inq_push+0x31c/0x440 net/sctp/inqueue.c:80
 sctp_backlog_rcv+0x30f/0x10b0 net/sctp/input.c:344
 sk_backlog_rcv include/net/sock.h:1030 [inline]
 __release_sock+0x256/0x640 net/core/sock.c:2768
 release_sock+0x98/0x2e0 net/core/sock.c:3300
 sctp_wait_for_connect+0x52a/0x9e0 net/sctp/socket.c:9306
 sctp_sendmsg_to_asoc+0x1c47/0x1f90 net/sctp/socket.c:1881
 sctp_sendmsg+0x3eaa/0x5460 net/sctp/socket.c:2027
 inet_sendmsg+0x15b/0x1d0 net/ipv4/af_inet.c:819
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 __sys_sendto+0x9ef/0xc70 net/socket.c:2036
 __do_sys_sendto net/socket.c:2048 [inline]
 __se_sys_sendto net/socket.c:2044 [inline]
 __x64_sys_sendto+0x19c/0x210 net/socket.c:2044
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Uninit was stored to memory at:
 sctp_inq_pop+0x155c/0x18f0 net/sctp/inqueue.c:201
 sctp_assoc_bh_rcv+0x1fa/0xdd0 net/sctp/associola.c:1000
 sctp_inq_push+0x31c/0x440 net/sctp/inqueue.c:80
 sctp_backlog_rcv+0x30f/0x10b0 net/sctp/input.c:344
 sk_backlog_rcv include/net/sock.h:1030 [inline]
 __release_sock+0x256/0x640 net/core/sock.c:2768
 release_sock+0x98/0x2e0 net/core/sock.c:3300
 sctp_wait_for_connect+0x52a/0x9e0 net/sctp/socket.c:9306
 sctp_sendmsg_to_asoc+0x1c47/0x1f90 net/sctp/socket.c:1881
 sctp_sendmsg+0x3eaa/0x5460 net/sctp/socket.c:2027
 inet_sendmsg+0x15b/0x1d0 net/ipv4/af_inet.c:819
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 __sys_sendto+0x9ef/0xc70 net/socket.c:2036
 __do_sys_sendto net/socket.c:2048 [inline]
 __se_sys_sendto net/socket.c:2044 [inline]
 __x64_sys_sendto+0x19c/0x210 net/socket.c:2044
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Uninit was created at:
 slab_post_alloc_hook mm/slab.h:524 [inline]
 slab_alloc_node mm/slub.c:3251 [inline]
 __kmalloc_node_track_caller+0xe0c/0x1510 mm/slub.c:4974
 kmalloc_reserve net/core/skbuff.c:354 [inline]
 __alloc_skb+0x545/0xf90 net/core/skbuff.c:426
 alloc_skb include/linux/skbuff.h:1126 [inline]
 sctp_packet_pack net/sctp/output.c:471 [inline]
 sctp_packet_transmit+0x194c/0x45a0 net/sctp/output.c:620
 sctp_outq_flush_transports net/sctp/outqueue.c:1163 [inline]
 sctp_outq_flush+0x17d9/0x5eb0 net/sctp/outqueue.c:1211
 sctp_outq_uncork+0x105/0x120 net/sctp/outqueue.c:758
 sctp_side_effects net/sctp/sm_sideeffect.c:1195 [inline]
 sctp_do_sm+0x946f/0x9b50 net/sctp/sm_sideeffect.c:1166
 sctp_assoc_bh_rcv+0xa15/0xdd0 net/sctp/associola.c:1054
 sctp_inq_push+0x31c/0x440 net/sctp/inqueue.c:80
 sctp_backlog_rcv+0x30f/0x10b0 net/sctp/input.c:344
 sk_backlog_rcv include/net/sock.h:1030 [inline]
 __release_sock+0x256/0x640 net/core/sock.c:2768
 release_sock+0x98/0x2e0 net/core/sock.c:3300
 sctp_wait_for_connect+0x52a/0x9e0 net/sctp/socket.c:9306
 sctp_sendmsg_to_asoc+0x1c47/0x1f90 net/sctp/socket.c:1881
 sctp_sendmsg+0x3eaa/0x5460 net/sctp/socket.c:2027
 inet_sendmsg+0x15b/0x1d0 net/ipv4/af_inet.c:819
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 __sys_sendto+0x9ef/0xc70 net/socket.c:2036
 __do_sys_sendto net/socket.c:2048 [inline]
 __se_sys_sendto net/socket.c:2044 [inline]
 __x64_sys_sendto+0x19c/0x210 net/socket.c:2044
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x44/0xae

CPU: 0 PID: 3479 Comm: syz-executor678 Not tainted 5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
=====================================================

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