BUG: unable to handle kernel NULL pointer dereference in sock_poll

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 7d3bf613e99a Merge tag 'libnvdimm-for-4.18' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1188a05f800000
kernel config: https://syzkaller.appspot.com/x/.config?x=f04d8d0a2afb789a
dashboard link: https://syzkaller.appspot.com/bug?extid=344bb0f46d7719cd9483
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=12b5841f800000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17f4005f800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+344bb0...@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)
random: sshd: uninitialized urandom read (32 bytes read)
BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
PGD 1b2931067 P4D 1b2931067 PUD 1d0ae1067 PMD 0
Oops: 0010 [#1] SMP KASAN
CPU: 0 PID: 4493 Comm: syz-executor249 Not tainted 4.17.0+ #92
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010: (null)
Code: Bad RIP value.
RSP: 0018:ffff8801b3bd7590 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8801b2994800 RCX: 1ffffffff10ea8e5
RDX: ffff8801b3bd7ab0 RSI: ffff8801ace8c980 RDI: ffff8801b378d800
RBP: ffff8801b3bd7700 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003677aeb7
R13: ffff8801b3bd7ab0 R14: ffff8801b2994812 R15: ffff8801b2994c58
FS: 00000000018d6880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001b2a10000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
sock_poll+0x1d1/0x710 net/socket.c:1156
vfs_poll+0x77/0x2a0 fs/select.c:40
do_pollfd fs/select.c:848 [inline]
do_poll fs/select.c:896 [inline]
do_sys_poll+0x6fd/0x1100 fs/select.c:990
__do_sys_poll fs/select.c:1048 [inline]
__se_sys_poll fs/select.c:1036 [inline]
__x64_sys_poll+0x189/0x510 fs/select.c:1036
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x43fcc9
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 6b 45 00 00 c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc32252d08 EFLAGS: 00000213 ORIG_RAX: 0000000000000007
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fcc9
RDX: 0000000000000003 RSI: 0000000000000001 RDI: 0000000020000040
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000213 R12: 00000000004015f0
R13: 0000000000401680 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
Dumping ftrace buffer:
(ftrace buffer empty)
CR2: 0000000000000000
---[ end trace c755e9b5f9cf1fa4 ]---
RIP: 0010: (null)
Code: Bad RIP value.
RSP: 0018:ffff8801b3bd7590 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8801b2994800 RCX: 1ffffffff10ea8e5
RDX: ffff8801b3bd7ab0 RSI: ffff8801ace8c980 RDI: ffff8801b378d800
RBP: ffff8801b3bd7700 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003677aeb7
R13: ffff8801b3bd7ab0 R14: ffff8801b2994812 R15: ffff8801b2994c58
FS: 00000000018d6880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001b2a10000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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[Tetsuo Handa]

On 2018/06/10 4:57, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    7d3bf613e99a Merge tag 'libnvdimm-for-4.18' of git://git.k..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1188a05f800000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f04d8d0a2afb789a
> dashboard link: https://syzkaller.appspot.com/bug?extid=344bb0f46d7719cd9483
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=12b5841f800000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17f4005f800000

This is a same report except s/epoll/poll/ .

----------
#include <sys/socket.h>
#include <sys/poll.h>
#define PF_SMC 43

int main(int argc, char *argv[])
{
int sfd = socket(PF_SMC, SOCK_STREAM, 0);
struct pollfd pfd = { .fd = sfd };
poll(&pfd, 1, 0);
return 0;
}
----------

#syz dup: BUG: unable to handle kernel NULL pointer dereference in corrupted