6659a2b9281752acd5e92c19e2aa9abf7e9f1753

Syzkaller hit 'general protection fault in hci_uart_tty_ioctl' bug.

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 8770 Comm: syz-executor.0 Not tainted 6.2.0 #4
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
RIP: 0010:hci_uart_tty_ioctl+0x244/0xc20 drivers/bluetooth/hci_ldisc.c:774
Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 cf 08 00 00 48 8b 9b b8 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 5f 08 00 00 44 8b 23 e9 14 ff
RSP: 0018:ffffc900022a7d10 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff8710057c
RDX: 0000000000000000 RSI: ffff888046df8000 RDI: ffff88801cf510b8
RBP: 0000000000000001 R08: 0000000000000001 R09: ffffed10039ea204
R10: ffff88801cf5101f R11: ffffed10039ea203 R12: ffff8880204eb000
R13: 0000000000000000 R14: ffffffffffffffe7 R15: 00000000800401c0
FS:  00007f203e7dd700(0000) GS:ffff88802ca00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005587ec7f32d8 CR3: 000000004629e000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 tty_ioctl+0xac0/0x1420 drivers/tty/tty_io.c:2784
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x198/0x210 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f203f0902fd
Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f203e7dcc58 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f203f1bc020 RCX: 00007f203f0902fd
RDX: 0000000000000000 RSI: 00000000800455c9 RDI: 0000000000000003
RBP: 00007f203f0fec89 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffee4615aef R14: 00007ffee4615ca0 R15: 00007f203e7dcdc0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:hci_uart_tty_ioctl+0x244/0xc20 drivers/bluetooth/hci_ldisc.c:774
Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 cf 08 00 00 48 8b 9b b8 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 5f 08 00 00 44 8b 23 e9 14 ff
RSP: 0018:ffffc900022a7d10 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff8710057c
RDX: 0000000000000000 RSI: ffff888046df8000 RDI: ffff88801cf510b8
RBP: 0000000000000001 R08: 0000000000000001 R09: ffffed10039ea204
R10: ffff88801cf5101f R11: ffffed10039ea203 R12: ffff8880204eb000
R13: 0000000000000000 R14: ffffffffffffffe7 R15: 00000000800401c0
FS:  00007f203e7dd700(0000) GS:ffff88807ec00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fae9539b740 CR3: 000000004629e000 CR4: 0000000000350ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	df 48 89             	fisttps -0x77(%rax)
   3:	fa                   	cli
   4:	48 c1 ea 03          	shr    $0x3,%rdx
   8:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   c:	0f 85 cf 08 00 00    	jne    0x8e1
  12:	48 8b 9b b8 00 00 00 	mov    0xb8(%rbx),%rbx
  19:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  20:	fc ff df
  23:	48 89 da             	mov    %rbx,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	0f b6 04 02          	movzbl (%rdx,%rax,1),%eax <-- trapping instruction
  2e:	84 c0                	test   %al,%al
  30:	74 08                	je     0x3a
  32:	3c 03                	cmp    $0x3,%al
  34:	0f 8e 5f 08 00 00    	jle    0x899
  3a:	44 8b 23             	mov    (%rbx),%r12d
  3d:	e9                   	.byte 0xe9
  3e:	14 ff                	adc    $0xff,%al


Syzkaller reproducer:
# {Threaded:true Collide:true Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true UseTmpDir:true HandleSegv:true Repro:false Trace:false LegacyOptions:{Fault:false FaultCall:0 FaultNth:0} InitResource:false}
ioctl$cec0_Groupc05c6104_25(0xffffffffffffffff, 0xc05c6104, 0x0)
r0 = openat$ptmx_syzgen(0xffffffffffffff9c, &(0x7f0000000000), 0x0, 0x0)
ioctl$ptmx_Group5423_1(r0, 0x5423, &(0x7f0000000000)=0xf)
r1 = openat$ttyprintk_syzgen(0xffffffffffffff9c, 0x0, 0x200, 0x0)
ioctl$ptmx_Group5407_2(r1, 0x5407, 0x0)
ioctl$ptmx_Group5402_3(r0, 0x400455c8, 0x0)
ioctl$ptmx_Group5402_3(r0, 0x800455c9, 0x0)


C reproducer: Note that I inserted a prink in the source code so that the C producer can easily trigger the bug.

// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <endian.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
#include <pthread.h>

uint64_t r[2] = {0xffffffffffffffff, 0xffffffffffffffff};

void *thr0(void *arg) {
    syscall(__NR_ioctl, r[0], 0x400455c8, 0ul);
}

void *thr1(void *arg) {
    syscall(__NR_ioctl, r[0], 0x800455c9, 0ul);
}

int main(void)
{
  pthread_t th[4];
  int i = 0;
  syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
  syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul);
  syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
  intptr_t res = 0;
  syscall(__NR_ioctl, -1, 0xc05c6104, 0ul);
  memcpy((void*)0x20000000, "/dev/pts/ptmx\000", 14);
  *(uint32_t*)0x20001000 = 0xf;
  for (i = 0;; i++) {
	  res = syscall(__NR_openat, 0xffffffffffffff9cul, 0x20000000ul, 0ul, 0ul);
	  if (res != -1)
	    r[0] = res;
	  else
	  	continue;

	  syscall(__NR_ioctl, r[0], 0x5423, 0x20001000ul);
	  pthread_create(&th[0], 0, thr0, 0);
	  pthread_create(&th[1], 0, thr1, 0);
	  pthread_join(th[0], 0);
	  pthread_join(th[1], 0);
	  close(r[0]);
  }
  return 0;
}