Skip to content
This repository has been archived by the owner on Sep 24, 2020. It is now read-only.

Commit

Permalink
tun/tap: sanitize TUNSETSNDBUF input
Browse files Browse the repository at this point in the history 
Syzkaller found several variants of the lockup below by setting negative
values with the TUNSETSNDBUF ioctl.  This patch adds a sanity check
to both the tun and tap versions of this ioctl.

  watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [repro:2389]
  Modules linked in:
  irq event stamp: 329692056
  hardirqs last  enabled at (329692055): [<ffffffff824b8381>] _raw_spin_unlock_irqrestore+0x31/0x75
  hardirqs last disabled at (329692056): [<ffffffff824b9e58>] apic_timer_interrupt+0x98/0xb0
  softirqs last  enabled at (35659740): [<ffffffff824bc958>] __do_softirq+0x328/0x48c
  softirqs last disabled at (35659731): [<ffffffff811c796c>] irq_exit+0xbc/0xd0
  CPU: 0 PID: 2389 Comm: repro Not tainted 4.14.0-rc7 #23
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
  task: ffff880009452140 task.stack: ffff880006a20000
  RIP: 0010:_raw_spin_lock_irqsave+0x11/0x80
  RSP: 0018:ffff880006a27c50 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff10
  RAX: ffff880009ac68d0 RBX: ffff880006a27ce0 RCX: 0000000000000000
  RDX: 0000000000000001 RSI: ffff880006a27ce0 RDI: ffff880009ac6900
  RBP: ffff880006a27c60 R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000001 R11: 000000000063ff00 R12: ffff880009ac6900
  R13: ffff880006a27cf8 R14: 0000000000000001 R15: ffff880006a27cf8
  FS:  00007f4be4838700(0000) GS:ffff88000cc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000020101000 CR3: 0000000009616000 CR4: 00000000000006f0
  Call Trace:
   prepare_to_wait+0x26/0xc0
   sock_alloc_send_pskb+0x14e/0x270
   ? remove_wait_queue+0x60/0x60
   tun_get_user+0x2cc/0x19d0
   ? __tun_get+0x60/0x1b0
   tun_chr_write_iter+0x57/0x86
   __vfs_write+0x156/0x1e0
   vfs_write+0xf7/0x230
   SyS_write+0x57/0xd0
   entry_SYSCALL_64_fastpath+0x1f/0xbe
  RIP: 0033:0x7f4be4356df9
  RSP: 002b:00007ffc18101c08 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
  RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f4be4356df9
  RDX: 0000000000000046 RSI: 0000000020101000 RDI: 0000000000000005
  RBP: 00007ffc18101c40 R08: 0000000000000001 R09: 0000000000000001
  R10: 0000000000000001 R11: 0000000000000293 R12: 0000559c75f64780
  R13: 00007ffc18101d30 R14: 0000000000000000 R15: 0000000000000000

Fixes: 33dccbb ("tun: Limit amount of queued packets per device")
Fixes: 20d29d7 ("net: macvtap driver")
Signed-off-by: Craig Gallek <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
  • Loading branch information
@kraigatgoog @davem330
kraigatgoog authored and davem330 committed Nov 1, 2017
1 parent d70eaa3 commit 9316192
Show file tree
Hide file tree
Showing 2 changed files with 6 additions and 0 deletions.
2 changes: 2 additions & 0 deletions drivers/net/tap.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1032,6 +1032,8 @@ static long tap_ioctl(struct file *file, unsigned int cmd,
case TUNSETSNDBUF:
if (get_user(s, sp))
return -EFAULT;
if (s <= 0)
return -EINVAL;

q->sk.sk_sndbuf = s;
return 0;
Expand Down
4 changes: 4 additions & 0 deletions drivers/net/tun.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2429,6 +2429,10 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
ret = -EFAULT;
break;
}
if (sndbuf <= 0) {
ret = -EINVAL;
break;
}

tun->sndbuf = sndbuf;
tun_set_sndbuf(tun);
Expand Down

0 comments on commit 9316192

Please sign in to comment.