Subject: KMSAN: uninit-value in ax25_connect

From: syzbot <[email-masked]>
Date: Tue, 28 Apr 2020 12:38:14 -0700

Hello,

syzbot found the following crash on:

HEAD commit:    8bbbc5cf kmsan: don't compile memmove
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=14c92275e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cd0e9a6b0e555cc3
dashboard link: https://syzkaller.appspot.com/bug?extid=c82752228ed975b0a623
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
userspace arch: i386
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11d74a75e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14694b45e00000

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

=====================================================
BUG: KMSAN: uninit-value in ax25_connect+0x92d/0x1e00 net/ax25/af_ax25.c:1203
CPU: 1 PID: 11844 Comm: syz-executor808 Not tainted 5.6.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x220 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
 ax25_connect+0x92d/0x1e00 net/ax25/af_ax25.c:1203
 __sys_connect_file net/socket.c:1857 [inline]
 __sys_connect+0x6f7/0x770 net/socket.c:1874
 __do_sys_connect net/socket.c:1885 [inline]
 __se_sys_connect net/socket.c:1882 [inline]
 __ia32_sys_connect+0xdb/0x130 net/socket.c:1882
 do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
 do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
 entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7ff7d99
Code: 90 e8 0b 00 00 00 f3 90 0f ae e8 eb f9 8d 74 26 00 89 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000ff80833c EFLAGS: 00000246 ORIG_RAX: 000000000000016a
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020000000
RDX: 000000000000003c RSI: 00000000080ea078 RDI: 00000000ff808390
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Local variable ----address@__sys_connect created at:
 __sys_connect+0xf7/0x770 net/socket.c:1870
 __sys_connect+0xf7/0x770 net/socket.c:1870
=====================================================

---
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