BUG: unable to handle kernel NULL pointer dereference in cfg80211_wext_siwrts

BUG: unable to handle kernel NULL pointer dereference in cfg80211_wext_siwrts

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    2f806c2a Merge branch 'net-ungraft-prio'
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=1032069ee00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5c90cac8f1f8c619
dashboard link: https://syzkaller.appspot.com/bug?extid=34b582cf32c1db008f8e
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

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+34b582cf32c1db008f8e@syzkaller.appspotmail.com

BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD a7499067 P4D a7499067 PUD 9a778067 PMD 0
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 12180 Comm: syz-executor.2 Not tainted 5.5.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffffc90001727a78 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff888218678540 RCX: ffffc9000e5df000
RDX: 1ffffffff1148744 RSI: 0000000000000008 RDI: ffff888218678540
RBP: ffffc90001727ab8 R08: ffff8880957ac0c0 R09: ffffed1015d2703d
R10: ffffed1015d2703c R11: ffff8880ae9381e3 R12: ffffffff88a438a0
R13: ffff88808f309000 R14: ffffc90001727bb0 R15: 0000000000000000
FS:  00007f1e9f870700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000094518000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  rdev_set_wiphy_params net/wireless/rdev-ops.h:542 [inline]
  cfg80211_wext_siwrts+0x265/0x8f0 net/wireless/wext-compat.c:267
  ioctl_standard_call+0xca/0x1d0 net/wireless/wext-core.c:1015
  wireless_process_ioctl.constprop.0+0x236/0x2b0 net/wireless/wext-core.c:953
  wext_ioctl_dispatch net/wireless/wext-core.c:986 [inline]
  wext_ioctl_dispatch net/wireless/wext-core.c:974 [inline]
  wext_handle_ioctl+0x106/0x1c0 net/wireless/wext-core.c:1047
  sock_ioctl+0x47d/0x790 net/socket.c:1112
  vfs_ioctl fs/ioctl.c:47 [inline]
  file_ioctl fs/ioctl.c:545 [inline]
  do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
  __do_sys_ioctl fs/ioctl.c:756 [inline]
  __se_sys_ioctl fs/ioctl.c:754 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45af49
Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f1e9f86fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 0000000020000040 RSI: 0000000000008b22 RDI: 0000000000000004
RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1e9f8706d4
R13: 00000000004c2837 R14: 00000000004d8b30 R15: 00000000ffffffff
Modules linked in:
CR2: 0000000000000000
---[ end trace 4579299d7d6f7d47 ]---
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffffc90001727a78 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff888218678540 RCX: ffffc9000e5df000
RDX: 1ffffffff1148744 RSI: 0000000000000008 RDI: ffff888218678540
RBP: ffffc90001727ab8 R08: ffff8880957ac0c0 R09: ffffed1015d2703d
R10: ffffed1015d2703c R11: ffff8880ae9381e3 R12: ffffffff88a438a0
R13: ffff88808f309000 R14: ffffc90001727bb0 R15: 0000000000000000
FS:  00007f1e9f870700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff5d5b8fc8 CR3: 0000000094518000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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Re: BUG: unable to handle kernel NULL pointer dereference in cfg80211_wext_siwrts

[Johannes Berg]

On Fri, 2020-01-10 at 11:11 -0800, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    2f806c2a Merge branch 'net-ungraft-prio'
> git tree:       net
> console output: https://syzkaller.appspot.com/x/log.txt?x=1032069ee00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=5c90cac8f1f8c619
> dashboard link: https://syzkaller.appspot.com/bug?extid=34b582cf32c1db008f8e
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> 
> Unfortunately, I don't have any reproducer for this crash yet.

It's quite likely also in virt_wifi, evidently that has some issues.

Cody, did you take a look at the previous report by any chance?

johannes

Re: BUG: unable to handle kernel NULL pointer dereference in cfg80211_wext_siwrts

[Justin Capella]

I noticed pfifo_qdisc_ops is exported as default_qdisc_ops is it
possible this is how rdev->ops is NULL

Seems unlikely, but thought I'd point it out.


On Fri, Jan 10, 2020 at 11:13 AM Johannes Berg
<johannes@sipsolutions.net> wrote:
>
> On Fri, 2020-01-10 at 11:11 -0800, syzbot wrote:
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit:    2f806c2a Merge branch 'net-ungraft-prio'
> > git tree:       net
> > console output: https://syzkaller.appspot.com/x/log.txt?x=1032069ee00000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=5c90cac8f1f8c619
> > dashboard link: https://syzkaller.appspot.com/bug?extid=34b582cf32c1db008f8e
> > compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> >
> > Unfortunately, I don't have any reproducer for this crash yet.
>
> It's quite likely also in virt_wifi, evidently that has some issues.
>
> Cody, did you take a look at the previous report by any chance?
>
> johannes
>

Re: BUG: unable to handle kernel NULL pointer dereference in cfg80211_wext_siwrts

[Dan Carpenter]

That's the wrong ops struct?  I think I was looking at the "previous
report" that Johannes mentioned where it was crashing because
virt_wifi doesn't implement a set_wiphy_params function.

Smatch says there are two other drivers, the libertas and ipw2x00 which
don't have a set_wiphy_params function either.  But maybe those handle
it a different way.

drivers/net/wireless/marvell/libertas/cfg.c | (null)                         | (struct cfg80211_ops)->set_wiphy_params | 0
drivers/net/wireless/virt_wifi.c | (null)                         | (struct cfg80211_ops)->set_wiphy_params | 0
drivers/net/wireless/intel/ipw2x00/libipw_module.c | (null)                         | (struct cfg80211_ops)->set_wiphy_params | 0

regards,
dan carpenter

On Fri, Jan 10, 2020 at 09:23:57PM -0800, Justin Capella wrote:
> I noticed pfifo_qdisc_ops is exported as default_qdisc_ops is it
> possible this is how rdev->ops is NULL
> 
> Seems unlikely, but thought I'd point it out.
> 
> 
> On Fri, Jan 10, 2020 at 11:13 AM Johannes Berg
> <johannes@sipsolutions.net> wrote:
> >
> > On Fri, 2020-01-10 at 11:11 -0800, syzbot wrote:
> > > Hello,
> > >
> > > syzbot found the following crash on:
> > >
> > > HEAD commit:    2f806c2a Merge branch 'net-ungraft-prio'
> > > git tree:       net
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=1032069ee00000
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=5c90cac8f1f8c619
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=34b582cf32c1db008f8e
> > > compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> > >
> > > Unfortunately, I don't have any reproducer for this crash yet.
> >
> > It's quite likely also in virt_wifi, evidently that has some issues.
> >
> > Cody, did you take a look at the previous report by any chance?
> >
> > johannes
> >
> 
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Re: BUG: unable to handle kernel NULL pointer dereference in cfg80211_wext_siwrts

[Johannes Berg]

On Mon, 2020-01-13 at 12:28 +0300, Dan Carpenter wrote:
> That's the wrong ops struct?  I think I was looking at the "previous
> report" that Johannes mentioned where it was crashing because
> virt_wifi doesn't implement a set_wiphy_params function.

Did I say that? Had forgotten by the time I got to this email ...

But thanks for the pointer (reminder?) I'll go through cfg80211 and fix
it there then.

johannes