On Mon, Feb 1, 2016 at 11:57 AM, Takashi Iwai <tiwai@xxxxxxx> wrote: > On Mon, 01 Feb 2016 11:26:57 +0100, > Dmitry Vyukov wrote: >> >> Hello, >> >> The following program triggers use-after-free in >> snd_seq_deliver_single_event (run in a tight parallel loop): >> >> // autogenerated by syzkaller (http://github.com/google/syzkaller) >> #include <pthread.h> >> #include <stdint.h> >> #include <string.h> >> #include <sys/syscall.h> >> #include <unistd.h> >> >> #ifndef SYS_mmap >> #define SYS_mmap 9 >> #endif >> #ifndef SYS_syz_open_dev >> #define SYS_syz_open_dev 1000001 >> #endif >> #ifndef SYS_ioctl >> #define SYS_ioctl 16 >> #endif >> #ifndef SYS_getpgrp >> #define SYS_getpgrp 111 >> #endif >> #ifndef SYS_migrate_pages >> #define SYS_migrate_pages 256 >> #endif >> #ifndef SYS_read >> #define SYS_read 0 >> #endif >> #ifndef SYS_write >> #define SYS_write 1 >> #endif >> #ifndef SYS_dup3 >> #define SYS_dup3 292 >> #endif >> >> long r[59]; >> >> void* thr(void* arg) >> { >> switch ((long)arg) { >> case 0: >> r[0] = syscall(SYS_mmap, 0x20000000ul, 0x47000ul, 0x3ul, 0x32ul, >> 0xfffffffffffffffful, 0x0ul); >> break; >> case 1: >> memcpy((void*)0x20000000, >> "\x2f\x64\x65\x76\x2f\x73\x65\x71\x75\x65\x6e\x63\x65\x72", >> 14); >> r[2] = >> syscall(SYS_open, "/dev/sequencer", 0x2ul, 0, 0, 0); >> break; >> case 2: >> r[3] = syscall(SYS_mmap, 0x20047000ul, 0x1000ul, 0x3ul, 0x32ul, >> 0xfffffffffffffffful, 0x0ul); >> break; >> case 3: >> r[4] = syscall(SYS_ioctl, r[2], 0x540ful, 0x20047ffcul, 0, 0, 0); >> if (r[4] != -1) >> r[5] = *(uint32_t*)0x20047ffc; >> break; >> case 4: >> r[6] = syscall(SYS_getpgrp, r[5], 0, 0, 0, 0, 0); >> break; >> case 5: >> r[7] = syscall(SYS_mmap, 0x20047000ul, 0x1000ul, 0x3ul, 0x32ul, >> 0xfffffffffffffffful, 0x0ul); >> break; >> case 6: >> r[8] = syscall(SYS_mmap, 0x20047000ul, 0x1000ul, 0x3ul, 0x32ul, >> 0xfffffffffffffffful, 0x0ul); >> break; >> case 7: >> *(uint64_t*)0x20047000 = (uint64_t)0x5; >> *(uint64_t*)0x20047000 = (uint64_t)0xfffffffffffffff8; >> r[11] = syscall(SYS_migrate_pages, r[6], 0xfful, 0x20047000ul, >> 0x20047000ul, 0, 0); >> break; >> case 8: >> memcpy((void*)0x20043684, >> "\x2f\x64\x65\x76\x2f\x64\x6d\x6d\x69\x64\x69\x23", 12); >> r[13] = syscall(SYS_open, "/dev/dmmidi2", 0x8a000ul, 0, 0, 0); >> break; >> case 9: >> r[14] = syscall(SYS_read, r[13], 0x20045000ul, 0x36ul, 0, 0, 0); >> break; >> case 10: >> *(uint8_t*)0x2000042c = (uint8_t)0x0; >> *(uint8_t*)0x2000042d = (uint8_t)0x9cf; >> *(uint8_t*)0x2000042e = (uint8_t)0x9; >> *(uint8_t*)0x2000042f = (uint8_t)0x0; >> *(uint64_t*)0x20000444 = (uint64_t)0x0; >> *(uint64_t*)0x2000044c = (uint64_t)0x989680; >> *(uint8_t*)0x20000454 = (uint8_t)0x2; >> *(uint8_t*)0x20000455 = (uint8_t)0x100000000; >> *(uint8_t*)0x20000456 = (uint8_t)0x8d; >> *(uint8_t*)0x20000457 = (uint8_t)0x7; >> *(uint8_t*)0x20000464 = (uint8_t)0x51b2; >> *(uint8_t*)0x20000465 = (uint8_t)0xfffffffffffff15a; >> *(uint8_t*)0x20000466 = (uint8_t)0x4; >> *(uint8_t*)0x20000467 = (uint8_t)0x4; >> *(uint32_t*)0x20000468 = (uint32_t)0xffffffff; >> *(uint8_t*)0x2000046c = (uint8_t)0x5; >> *(uint8_t*)0x2000046d = (uint8_t)0xfffffffffffffff8; >> *(uint8_t*)0x2000046e = (uint8_t)0x401; >> *(uint8_t*)0x2000046f = (uint8_t)0x5; >> *(uint64_t*)0x20000484 = (uint64_t)0x4; >> *(uint64_t*)0x2000048c = (uint64_t)0x0; >> *(uint8_t*)0x20000494 = (uint8_t)0xc2c1; >> *(uint8_t*)0x20000495 = (uint8_t)0x1; >> *(uint8_t*)0x20000496 = (uint8_t)0x6b; >> *(uint8_t*)0x20000497 = (uint8_t)0x6; >> *(uint8_t*)0x200004a0 = (uint8_t)0xfffffffffffffffa; >> *(uint8_t*)0x200004a1 = (uint8_t)0x81; >> *(uint8_t*)0x200004a2 = (uint8_t)0x0; >> *(uint8_t*)0x200004a3 = (uint8_t)0xa6; >> *(uint8_t*)0x200004a4 = (uint8_t)0x400; >> *(uint8_t*)0x200004a5 = (uint8_t)0x3ff; >> *(uint8_t*)0x200004a6 = (uint8_t)0x8; >> *(uint8_t*)0x200004a7 = (uint8_t)0x3; >> *(uint64_t*)0x200004bc = (uint64_t)0x0; >> *(uint64_t*)0x200004c4 = (uint64_t)0x0; >> *(uint8_t*)0x200004cc = (uint8_t)0x9e; >> *(uint8_t*)0x200004cd = (uint8_t)0x7ff; >> *(uint8_t*)0x200004ce = (uint8_t)0x7fff; >> *(uint8_t*)0x200004cf = (uint8_t)0x9; >> *(uint8_t*)0x200004e0 = (uint8_t)0xa; >> *(uint32_t*)0x200004e4 = (uint32_t)0x6; >> *(uint32_t*)0x200004e8 = (uint32_t)0xffffffff; >> r[57] = syscall(SYS_write, r[2], 0x2000042cul, 0x78ul, 0, 0, 0); >> break; >> case 11: >> r[58] = syscall(SYS_dup3, r[13], r[2], 0x80000ul, 0, 0, 0); >> break; >> } >> return 0; >> } >> >> int main() >> { >> long i; >> pthread_t th[12]; >> >> memset(r, -1, sizeof(r)); >> for (i = 0; i < 12; i++) { >> pthread_create(&th[i], 0, thr, (void*)i); >> usleep(10000); >> } >> for (i = 0; i < 12; i++) { >> pthread_create(&th[i], 0, thr, (void*)i); >> if (i % 2 == 0) >> usleep(10000); >> } >> usleep(100000); >> return 0; >> } >> >> >> ================================================================== >> BUG: KASAN: use-after-free in do_raw_spin_lock+0x281/0x2b0 at addr >> ffff88002abf1654 >> Read of size 4 by task syz-executor/13987 >> ============================================================================= >> BUG kmalloc-96 (Not tainted): kasan: bad access detected >> ----------------------------------------------------------------------------- >> >> INFO: Allocated in snd_midi_event_new+0x73/0x200 age=10 cpu=0 pid=13996 >> [< none >] ___slab_alloc+0x564/0x5b0 mm/slub.c:2470 >> [< none >] __slab_alloc+0x66/0xc0 mm/slub.c:2499 >> [< inline >] slab_alloc_node mm/slub.c:2562 >> [< inline >] slab_alloc mm/slub.c:2604 >> [< none >] kmem_cache_alloc_trace+0x25c/0x300 mm/slub.c:2621 >> [< inline >] kmalloc include/linux/slab.h:463 >> [< inline >] kzalloc include/linux/slab.h:607 >> [< none >] snd_midi_event_new+0x73/0x200 >> sound/core/seq/seq_midi_event.c:120 >> [< none >] snd_virmidi_input_open+0xfd/0x380 >> sound/core/seq/seq_virmidi.c:214 >> [< none >] open_substream+0x3eb/0x780 sound/core/rawmidi.c:269 >> [< none >] rawmidi_open_priv+0x144/0x300 sound/core/rawmidi.c:312 >> [< none >] snd_rawmidi_open+0x3fb/0xa90 sound/core/rawmidi.c:416 >> [< none >] soundcore_open+0x30f/0x640 sound/sound_core.c:639 >> [< none >] chrdev_open+0x22a/0x4c0 fs/char_dev.c:388 >> [< none >] do_dentry_open+0x6a2/0xcb0 fs/open.c:736 >> [< none >] vfs_open+0x17b/0x1f0 fs/open.c:853 >> [< inline >] do_last fs/namei.c:3254 >> [< none >] path_openat+0xde9/0x5e30 fs/namei.c:3386 >> [< none >] do_filp_open+0x18e/0x250 fs/namei.c:3421 >> [< none >] do_sys_open+0x1fc/0x420 fs/open.c:1022 >> [< inline >] SYSC_open fs/open.c:1040 >> [< none >] SyS_open+0x2d/0x40 fs/open.c:1035 >> >> INFO: Freed in snd_midi_event_free+0x43/0x60 age=17 cpu=0 pid=13996 >> [< none >] __slab_free+0x1fc/0x320 mm/slub.c:2680 >> [< inline >] slab_free mm/slub.c:2835 >> [< none >] kfree+0x2ac/0x2c0 mm/slub.c:3664 >> [< none >] snd_midi_event_free+0x43/0x60 >> sound/core/seq/seq_midi_event.c:142 >> [< none >] snd_virmidi_input_close+0x87/0x120 >> sound/core/seq/seq_virmidi.c:261 >> [< none >] close_substream.part.14+0xda/0x540 sound/core/rawmidi.c:486 >> [< inline >] close_substream sound/core/rawmidi.c:514 >> [< none >] rawmidi_release_priv+0x1e4/0x250 sound/core/rawmidi.c:504 >> [< none >] snd_rawmidi_release+0x62/0xf0 sound/core/rawmidi.c:539 >> [< none >] __fput+0x236/0x780 fs/file_table.c:208 >> [< none >] ____fput+0x15/0x20 fs/file_table.c:244 >> [< none >] task_work_run+0x170/0x210 kernel/task_work.c:115 >> [< inline >] exit_task_work include/linux/task_work.h:21 >> [< none >] do_exit+0x8b5/0x2cb0 kernel/exit.c:748 >> [< none >] do_group_exit+0x108/0x330 kernel/exit.c:878 >> [< none >] get_signal+0x5e4/0x14f0 kernel/signal.c:2307 >> [< none >] do_signal+0x83/0x1c90 arch/x86/kernel/signal.c:712 >> [< none >] exit_to_usermode_loop+0x1a5/0x210 >> arch/x86/entry/common.c:247 >> [< inline >] prepare_exit_to_usermode arch/x86/entry/common.c:282 >> [< none >] syscall_return_slowpath+0x2ba/0x340 >> arch/x86/entry/common.c:344 >> >> INFO: Slab 0xffffea0000aafc00 objects=28 used=11 fp=0xffff88002abf0470 >> flags=0x1fffc0000004080 >> INFO: Object 0xffff88002abf1630 @offset=5680 fp=0xffff88002abf06a8 >> CPU: 1 PID: 13987 Comm: syz-executor Tainted: G B 4.5.0-rc1+ #305 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >> 00000000ffffffff ffff880061aaf7d8 ffffffff82be11ad ffff88003e804900 >> ffff88002abf1630 ffff88002abf0000 ffff880061aaf808 ffffffff8175b454 >> ffff88003e804900 ffffea0000aafc00 ffff88002abf1630 000000000000000a >> >> Call Trace: >> [<ffffffff81764e3e>] __asan_report_load4_noabort+0x3e/0x40 >> mm/kasan/report.c:294 >> [< inline >] debug_spin_lock_before kernel/locking/spinlock_debug.c:83 >> [<ffffffff814663d1>] do_raw_spin_lock+0x281/0x2b0 >> kernel/locking/spinlock_debug.c:135 >> [< inline >] __raw_spin_lock_irqsave >> include/linux/spinlock_api_smp.h:119 >> [<ffffffff86652b67>] _raw_spin_lock_irqsave+0xa7/0xd0 >> kernel/locking/spinlock.c:159 >> [<ffffffff852bb6a7>] snd_midi_event_decode+0x1f7/0x5c0 >> sound/core/seq/seq_midi_event.c:391 >> [< inline >] snd_virmidi_dev_receive_event >> sound/core/seq/seq_virmidi.c:95 >> [<ffffffff852ce754>] snd_virmidi_event_input+0x214/0x310 >> sound/core/seq/seq_virmidi.c:133 >> [<ffffffff852a7934>] >> snd_seq_deliver_single_event.constprop.11+0x3f4/0x740 >> sound/core/seq/seq_clientmgr.c:634 >> [<ffffffff852a7da2>] snd_seq_deliver_event+0x122/0x800 >> sound/core/seq/seq_clientmgr.c:828 >> [<ffffffff852a9186>] snd_seq_kernel_client_dispatch+0x126/0x170 >> sound/core/seq/seq_clientmgr.c:2401 >> [< inline >] snd_seq_oss_dispatch >> sound/core/seq/oss/seq_oss_device.h:151 >> [<ffffffff852ca423>] snd_seq_oss_midi_reset+0x303/0x4a0 >> sound/core/seq/oss/seq_oss_midi.c:481 >> [<ffffffff852bd490>] snd_seq_oss_reset+0x130/0x260 >> sound/core/seq/oss/seq_oss_init.c:469 >> [<ffffffff852bd631>] snd_seq_oss_release+0x71/0x130 >> sound/core/seq/oss/seq_oss_init.c:425 >> [<ffffffff852bbcca>] odev_release+0x5a/0x80 sound/core/seq/oss/seq_oss.c:155 >> [<ffffffff817c0156>] __fput+0x236/0x780 fs/file_table.c:208 >> [<ffffffff817c0725>] ____fput+0x15/0x20 fs/file_table.c:244 >> [<ffffffff813b14e0>] task_work_run+0x170/0x210 kernel/task_work.c:115 >> [< inline >] tracehook_notify_resume include/linux/tracehook.h:191 >> [<ffffffff810066b1>] exit_to_usermode_loop+0x1d1/0x210 >> arch/x86/entry/common.c:251 >> [< inline >] prepare_exit_to_usermode arch/x86/entry/common.c:282 >> [<ffffffff810084ea>] syscall_return_slowpath+0x2ba/0x340 >> arch/x86/entry/common.c:344 >> [<ffffffff86653322>] int_ret_from_sys_call+0x25/0x9f >> arch/x86/entry/entry_64.S:281 > > Looks like a race at closing virmidi device. > Does the patch below fix it? This seems to help. > thanks, > > Takashi > > --- > diff --git a/sound/core/seq/seq_virmidi.c b/sound/core/seq/seq_virmidi.c > index 3da2d48610b3..f71aedfb408c 100644 > --- a/sound/core/seq/seq_virmidi.c > +++ b/sound/core/seq/seq_virmidi.c > @@ -254,9 +254,13 @@ static int snd_virmidi_output_open(struct snd_rawmidi_substream *substream) > */ > static int snd_virmidi_input_close(struct snd_rawmidi_substream *substream) > { > + struct snd_virmidi_dev *rdev = substream->rmidi->private_data; > struct snd_virmidi *vmidi = substream->runtime->private_data; > - snd_midi_event_free(vmidi->parser); > + > + write_lock_irq(&rdev->filelist_lock); > list_del(&vmidi->list); > + write_unlock_irq(&rdev->filelist_lock); > + snd_midi_event_free(vmidi->parser); > substream->runtime->private_data = NULL; > kfree(vmidi); > return 0; _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
