[alsa-devel] UBSAN: Undefined behaviour in sound/core/timer.c

[air icy]

Hi,
This bug was found in Linux Kernel v4.18-rc2
1521                                         if (id.subdevice < 0)
1522                                                 id.subdevice = 0;
1523                                         else
1524                                                 id.subdevice++;
1525                                 }
1526                         }

$ cat report5
================================================================================
UBSAN: Undefined behaviour in sound/core/timer.c:1524:19
signed integer overflow:
2147483647 + 1 cannot be represented in type 'int'
CPU: 0 PID: 7737 Comm: syz-executor0 Not tainted 4.18.0-rc1 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.10.2-0-g5f4c7b1-prebuilt.qemu-project.org 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x122/0x1c8 lib/dump_stack.c:113
 ubsan_epilogue+0x12/0x86 lib/ubsan.c:159
 handle_overflow+0x1c2/0x21f lib/ubsan.c:190
 __ubsan_handle_add_overflow+0x2a/0x31 lib/ubsan.c:198
 snd_timer_user_next_device sound/core/timer.c:1524 [inline]
 __snd_timer_user_ioctl+0x204d/0x2520 sound/core/timer.c:1939
 snd_timer_user_ioctl+0x67/0x95 sound/core/timer.c:1994
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1e8/0x1340 fs/ioctl.c:686
 ksys_ioctl+0x9c/0xb0 fs/ioctl.c:701
 __do_sys_ioctl fs/ioctl.c:708 [inline]
 __se_sys_ioctl fs/ioctl.c:706 [inline]
 __x64_sys_ioctl+0x81/0xd0 fs/ioctl.c:706
 do_syscall_64+0xb8/0x3a0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455a09
Code: 1d ba 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 eb b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f9d190edc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f9d190ee6d4 RCX: 0000000000455a09
RDX: 0000000020000200 RSI: 00000000c0145401 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000359 R14: 00000000006fa0f8 R15: 0000000000000000
================================================================================
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=7
sclass=netlink_route_socket pig=7762 comm=syz-executor0
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=7
sclass=netlink_route_socket pig=7766 comm=syz-executor0
sr 1:0:0:0: [sr0] tag#0 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
sr 1:0:0:0: [sr0] tag#0 Sense Key : Illegal Request [current]
sr 1:0:0:0: [sr0] tag#0 Add. Sense: Invalid command operation code
sr 1:0:0:0: [sr0] tag#0 CDB: Write(10) 2a 00 00 00 00 00 00 00 40 00
print_req_error: critical target error, dev sr0, sector 0
...
sr 1:0:0:0: [sr0] tag#0 FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK
sr 1:0:0:0: [sr0] tag#0 CDB: Write(16) 8a d0 47 23 7d 8d 1b 64 4d f6 e2 4e
sr 1:0:0:0: [sr0] tag#0 FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK
sr 1:0:0:0: [sr0] tag#0 CDB: Write(16) 8a d0 47 23 7d 8d 1b 64 4d f6 e2 4e
audit: type=1326 audit(1529712149.140:4): auid=4294967295 uid=0 gid=0
ses=4294967295 subj=kernel pid=8226 comm="syz-executor1"
exe="/syz-executor1" sig=31 arch=c000003e syscall=202 compat=0
ip=0x455a09 code=0x0

This bug can be repro, if you need it, please tell me.

bugzilla url: https://bugzilla.kernel.org/show_bug.cgi?id=200213
Thanks,
Icytxw