KMSAN: uninit-value in rds_connect

KMSAN: uninit-value in rds_connect

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    2dca2cbde67a kmsan: fix build warnings with CONFIG_KMSAN=n
git tree:       https://github.com/google/kmsan.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=1519734a400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=820d6393634b55e3
dashboard link: https://syzkaller.appspot.com/bug?extid=0049bebbf3042dbd2e8f
compiler:       clang version 8.0.0 (trunk 339414)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+0049bebbf3042dbd2e8f@syzkaller.appspotmail.com

RDX: 0000000000000000 RSI: 0000000020000380 RDI: 00000000000001ff
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00000000004cd2e8 R14: 00000000004c3d93 R15: 0000000000000003
==================================================================
BUG: KMSAN: uninit-value in rds_connect+0x213/0x950 net/rds/af_rds.c:511
CPU: 0 PID: 8117 Comm: syz-executor6 Not tainted 4.19.0-rc1+ #36
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+0x14b/0x190 lib/dump_stack.c:113
  kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956
  __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645
  rds_connect+0x213/0x950 net/rds/af_rds.c:511
  __sys_connect+0x64e/0x750 net/socket.c:1662
  __do_sys_connect net/socket.c:1673 [inline]
  __se_sys_connect net/socket.c:1670 [inline]
  __x64_sys_connect+0xd8/0x120 net/socket.c:1670
  do_syscall_64+0x15b/0x220 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x457089
Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f7090fc1c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f7090fc26d4 RCX: 0000000000457089
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004cb710 R14: 00000000004c320b R15: 0000000000000000

Local variable description: ----address@__sys_connect
Variable was created at:
  __sys_connect+0x6a/0x750 net/socket.c:1645
  __do_sys_connect net/socket.c:1673 [inline]
  __se_sys_connect net/socket.c:1670 [inline]
  __x64_sys_connect+0xd8/0x120 net/socket.c:1670
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with  
syzbot.

Re: KMSAN: uninit-value in rds_connect

[Santosh Shilimkar]

On 8/30/2018 11:31 AM, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    2dca2cbde67a kmsan: fix build warnings with CONFIG_KMSAN=n
> git tree:       https://github.com/google/kmsan.git/master
> console output: https://syzkaller.appspot.com/x/log.txt?x=1519734a400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=820d6393634b55e3
> dashboard link: 
> https://syzkaller.appspot.com/bug?extid=0049bebbf3042dbd2e8f
> compiler:       clang version 8.0.0 (trunk 339414)
> 
> Unfortunately, I don't have any reproducer for this crash yet.
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+0049bebbf3042dbd2e8f@syzkaller.appspotmail.com
> 
OK. Will send the fix to address this.

Regards,
Santosh

Re: KMSAN: uninit-value in rds_connect

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit:    25114c64b719 kmsan: unpoison pages moved from iov_iter to ..
git tree:       https://github.com/google/kmsan.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=14465da6400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3431f03869413153
dashboard link: https://syzkaller.appspot.com/bug?extid=0049bebbf3042dbd2e8f
compiler:       clang version 8.0.0 (trunk 339414)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13b8513e400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10d64e96400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+0049bebbf3042dbd2e8f@syzkaller.appspotmail.com

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
==================================================================
BUG: KMSAN: uninit-value in rds_connect+0x213/0x950 net/rds/af_rds.c:511
CPU: 0 PID: 4780 Comm: syz-executor239 Not tainted 4.19.0-rc1+ #38
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+0x14b/0x190 lib/dump_stack.c:113
  kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956
  __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645
  rds_connect+0x213/0x950 net/rds/af_rds.c:511
  __sys_connect+0x64e/0x750 net/socket.c:1662
  __do_sys_connect net/socket.c:1673 [inline]
  __se_sys_connect net/socket.c:1670 [inline]
  __x64_sys_connect+0xd8/0x120 net/socket.c:1670
  do_syscall_64+0x15b/0x220 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x440199
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fff5f41c118 EFLAGS: 00000213 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440199
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000213 R12: 0000000000401a20
R13: 0000000000401ab0 R14: 0000000000000000 R15: 0000000000000000

Local variable description: ----address@__sys_connect
Variable was created at:
  __sys_connect+0x6a/0x750 net/socket.c:1645
  __do_sys_connect net/socket.c:1673 [inline]
  __se_sys_connect net/socket.c:1670 [inline]
  __x64_sys_connect+0xd8/0x120 net/socket.c:1670
==================================================================