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Date: Thu, 21 Apr 2016 08:21:35 +0200 From: Takashi Iwai <tiwai@...e.de> To: Baozeng Ding <sploving1@...il.com> Cc: yang.jie@...el.com, koro.chen@...iatek.com, lars@...afoo.de, perex@...ex.cz, alsa-devel@...a-project.org, linux-kernel@...r.kernel.org Subject: Re: Sound: BUG: KASAN: use-after-free in kill_fasync On Thu, 21 Apr 2016 04:13:13 +0200, Baozeng Ding wrote: > > > > On 2016/4/6 19:37, Baozeng Ding wrote: > > > > > > On 2016/4/5 22:18, Takashi Iwai wrote: > >> On Tue, 05 Apr 2016 15:51:30 +0200, > >> Baozeng Ding wrote: > >>> Hi all, > >>> I've got the following report (use-after-free in kill_fasync) while > >>> running syzkaller. > >>> Unfortunately no reproducer.The kernel version is 4.5 (on Mar 16 commit > >>> 09fd671ccb2475436bd5f597f751ca4a7d177aea). > >>> > >>> ================================================================== > >>> BUG: KASAN: use-after-free in kill_fasync+0x3fb/0x420 at addr > >>> ffff880067691d88 > >>> Read of size 8 by task swapper/2/0 > >>> ============================================================================= > >>> > >>> BUG kmalloc-2048 (Not tainted): kasan: bad access detected > >>> ----------------------------------------------------------------------------- > >>> > >>> > >>> Disabling lock debugging due to kernel taint > >>> INFO: Allocated in 0xbbbbbbbbbbbbbbbb age=18446678412249576073 > >>> cpu=2245704320 pid=-1 > >>> [< inline >] kmalloc /kernel/include/linux/slab.h:472 > >>> [< inline >] kzalloc /kernel/include/linux/slab.h:616 > >>> [< none >] snd_pcm_attach_substream+0x3b4/0xb10 > >>> /kernel/sound/core/pcm.c:966 > >>> [< none >] ___slab_alloc+0x4c7/0x500 /kernel/mm/slub.c:2446 > >>> [< none >] __slab_alloc+0x4c/0x90 /kernel/mm/slub.c:2475 > >>> [< inline >] slab_alloc_node /kernel/mm/slub.c:2538 > >>> [< inline >] slab_alloc /kernel/mm/slub.c:2580 > >>> [< none >] kmem_cache_alloc_trace+0x262/0x300 > >>> /kernel/mm/slub.c:2597 > >>> [< inline >] kmalloc /kernel/include/linux/slab.h:472 > >>> [< inline >] kzalloc /kernel/include/linux/slab.h:616 > >>> [< none >] snd_pcm_attach_substream+0x3b4/0xb10 > >>> /kernel/sound/core/pcm.c:966 > >>> [< none >] snd_pcm_open_substream+0x84/0x450 > >>> /kernel/sound/core/pcm_native.c:2262 > >>> [< inline >] snd_pcm_oss_open_file > >>> /kernel/sound/core/oss/pcm_oss.c:2346 > >>> [< none >] snd_pcm_oss_open.part.17+0x5a4/0x1100 > >>> /kernel/sound/core/oss/pcm_oss.c:2428 > >>> [< none >] snd_pcm_oss_open+0x35/0x50 > >>> /kernel/sound/core/oss/pcm_oss.c:2392 > >>> [< none >] soundcore_open+0x30f/0x640 > >>> /kernel/sound/sound_core.c:639 > >>> [< none >] chrdev_open+0x22a/0x4c0 /kernel/fs/char_dev.c:388 > >>> [< none >] do_dentry_open+0x6a2/0xcb0 /kernel/fs/open.c:736 > >>> [< none >] vfs_open+0x17b/0x1f0 /kernel/fs/open.c:853 > >>> [< inline >] do_last /kernel/fs/namei.c:3258 > >>> [< none >] path_openat+0x4837/0x5830 /kernel/fs/namei.c:3394 > >>> [< none >] do_filp_open+0x18e/0x250 /kernel/fs/namei.c:3429 > >>> [< none >] do_sys_open+0x201/0x420 /kernel/fs/open.c:1022 > >>> [< inline >] SYSC_open /kernel/fs/open.c:1040 > >>> [< none >] SyS_open+0x2d/0x40 /kernel/fs/open.c:1035 > >>> INFO: Freed in 0x10000b076 age=18446678416544543380 cpu=0 pid=0 > >>> [< none >] snd_pcm_detach_substream+0x134/0x280 > >>> /kernel/sound/core/pcm.c:1017 > >>> [< none >] __slab_free+0x1e8/0x300 /kernel/mm/slub.c:2657 > >>> [< inline >] slab_free /kernel/mm/slub.c:2810 > >>> [< none >] kfree+0x24e/0x2d0 /kernel/mm/slub.c:3661 > >>> [< none >] snd_pcm_detach_substream+0x134/0x280 > >>> /kernel/sound/core/pcm.c:1017 > >>> [< none >] snd_pcm_release_substream.part.38+0x219/0x2f0 > >>> /kernel/sound/core/pcm_native.c:2250 > >>> [< none >] snd_pcm_release_substream+0x59/0x70 > >>> /kernel/sound/core/pcm_native.c:2251 > >>> [< none >] snd_pcm_oss_release_file+0x45/0xb0 > >>> /kernel/sound/core/oss/pcm_oss.c:2305 > >>> [< none >] snd_pcm_oss_release+0xfa/0x250 > >>> /kernel/sound/core/oss/pcm_oss.c:2485 > >>> [< none >] __fput+0x236/0x780 /kernel/fs/file_table.c:208 > >>> [< none >] ____fput+0x15/0x20 /kernel/fs/file_table.c:244 > >>> [< none >] task_work_run+0x16b/0x200 > >>> /kernel/kernel/task_work.c:115 > >>> [< inline >] exit_task_work > >>> /kernel/include/linux/task_work.h:21 > >>> [< none >] do_exit+0x87f/0x2c90 /kernel/kernel/exit.c:748 > >>> [< none >] do_group_exit+0x108/0x330 > >>> /kernel/kernel/exit.c:878 > >>> [< inline >] SYSC_exit_group /kernel/kernel/exit.c:889 > >>> [< none >] SyS_exit_group+0x1d/0x20 /kernel/kernel/exit.c:887 > >>> [< none >] entry_SYSCALL_64_fastpath+0x23/0xc1 > >>> /kernel/arch/x86/entry/entry_64.S:207 > >>> INFO: Slab 0xffffea00019da400 objects=13 used=8 fp=0xffff880067691be0 > >>> flags=0x5fffc0000004080 > >>> INFO: Object 0xffff880067691bd8 @offset=7128 fp=0xbbbbbbbbbbbbbbbb > >>> Call Trace: > >>> <IRQ> [< inline >] __dump_stack /kernel/lib/dump_stack.c:15 > >>> <IRQ> [<ffffffff82945051>] dump_stack+0xb3/0x112 > >>> /kernel/lib/dump_stack.c:51 > >>> [<ffffffff817009ad>] print_trailer+0x10d/0x190 /kernel/mm/slub.c:668 > >>> [<ffffffff817074af>] object_err+0x2f/0x40 /kernel/mm/slub.c:675 > >>> [< inline >] print_address_description > >>> /kernel/mm/kasan/report.c:138 > >>> [<ffffffff81709ca5>] kasan_report_error+0x215/0x530 > >>> /kernel/mm/kasan/report.c:236 > >>> [< inline >] ? spin_lock > >>> /kernel/include/linux/spinlock.h:302 > >>> [<ffffffff84a1c550>] ? snd_pcm_stream_lock+0x80/0xd0 > >>> /kernel/sound/core/pcm_native.c:104 > >>> [< inline >] kasan_report /kernel/mm/kasan/report.c:259 > >>> [<ffffffff8170a0be>] __asan_report_load8_noabort+0x3e/0x40 > >>> /kernel/mm/kasan/report.c:280 > >>> [<ffffffff81792a0b>] ? kill_fasync+0x3fb/0x420 > >>> /kernel/fs/fcntl.c:729 > >>> [<ffffffff81792a0b>] kill_fasync+0x3fb/0x420 /kernel/fs/fcntl.c:729 > >>> [<ffffffff84a36e08>] snd_pcm_period_elapsed+0x1c8/0x230 > >>> /kernel/sound/core/pcm_lib.c:1890 > >>> [<ffffffff84b6e2e0>] ? get_bound_vga.isra.21.part.22+0x140/0x140 > >>> /kernel/sound/pci/hda/hda_intel.c:1327 > >>> [<ffffffff84b0637d>] stream_update+0xad/0xe0 > >>> /kernel/sound/pci/hda/hda_controller.c:923 > >>> [<ffffffff84c1583e>] snd_hdac_bus_handle_stream_irq+0x24e/0x350 > >>> /kernel/sound/hda/hdac_controller.c:449 > >>> [<ffffffff84b062d0>] ? azx_init_chip+0x100/0x100 > >>> /kernel/sound/pci/hda/hda_controller.c:890 > >>> [<ffffffff84b04d24>] ? azx_interrupt+0x14/0x4d0 > >>> /kernel/sound/pci/hda/hda_controller.c:929 > >>> [<ffffffff84b04eee>] azx_interrupt+0x1de/0x4d0 > >>> /kernel/sound/pci/hda/hda_controller.c:954 > >>> [<ffffffff84b04d10>] ? azx_stop_chip+0x20/0x20 > >>> /kernel/sound/pci/hda/hda_controller.c:908 > >>> [<ffffffff8143d9e3>] handle_irq_event_percpu+0xf3/0x790 > >>> /kernel/kernel/irq/handle.c:145 > >>> [<ffffffff8143e127>] handle_irq_event+0xa7/0x140 > >>> /kernel/kernel/irq/handle.c:192 > >>> [<ffffffff81447f81>] handle_edge_irq+0x1e1/0x8d0 > >>> /kernel/kernel/irq/chip.c:623 > >>> [< inline >] generic_handle_irq_desc > >>> /kernel/include/linux/irqdesc.h:146 > >>> [<ffffffff811ad739>] handle_irq+0x109/0x2a0 > >>> /kernel/arch/x86/kernel/irq_64.c:78 > >>> [< inline >] ? rcu_lock_release > >>> /kernel/include/linux/rcupdate.h:491 > >>> [< inline >] ? rcu_read_unlock > >>> /kernel/include/linux/rcupdate.h:926 > >>> [< inline >] ? __atomic_notifier_call_chain > >>> /kernel/kernel/notifier.c:184 > >>> [<ffffffff81369c4f>] ? atomic_notifier_call_chain+0xbf/0x140 > >>> /kernel/kernel/notifier.c:193 > >>> [<ffffffff81369b90>] ? __atomic_notifier_call_chain+0x150/0x150 > >>> /kernel/include/linux/rcupdate.h:922 > >>> [<ffffffff811ac36d>] do_IRQ+0x7d/0x1a0 > >>> /kernel/arch/x86/kernel/irq.c:240 > >>> [<ffffffff85dac40c>] common_interrupt+0x8c/0x8c > >>> /kernel/arch/x86/entry/entry_64.S:454 > >>> <EOI> [<ffffffff812245c6>] ? native_safe_halt+0x6/0x10 > >>> /kernel/./arch/x86/include/asm/irqflags.h:49 > >>> [<ffffffff81405ced>] ? trace_hardirqs_on+0xd/0x10 > >>> /kernel/kernel/locking/lockdep.c:2635 > >>> [< inline >] arch_safe_halt > >>> /kernel/./arch/x86/include/asm/paravirt.h:117 > >>> [<ffffffff811bf152>] default_idle+0x22/0x2d0 > >>> /kernel/arch/x86/kernel/process.c:307 > >>> [<ffffffff811c053a>] arch_cpu_idle+0xa/0x10 > >>> /kernel/arch/x86/kernel/process.c:298 > >>> [<ffffffff813eb618>] default_idle_call+0x48/0x70 > >>> /kernel/kernel/sched/idle.c:93 > >>> [< inline >] cpuidle_idle_call > >>> /kernel/kernel/sched/idle.c:151 > >>> [< inline >] cpu_idle_loop /kernel/kernel/sched/idle.c:242 > >>> [<ffffffff813ebaa7>] cpu_startup_entry+0x467/0x600 > >>> /kernel/kernel/sched/idle.c:291 > >>> [<ffffffff81201432>] start_secondary+0x2b2/0x380 > >>> /kernel/arch/x86/kernel/smpboot.c:259 > >>> [<ffffffff81201180>] ? set_cpu_sibling_map+0x18a0/0x18a0 > >>> /kernel/include/linux/topology.h:80 > >>> Memory state around the buggy address: > >>> ffff880067691c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > >>> ffff880067691d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > >>> >ffff880067691d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > >>> ^ > >>> ffff880067691e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > >>> ffff880067691e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > >>> ================================================================== > >>> > >>> It seems that in function snd_pcm_detach_substream, when freeing > >>> runtime > >>> structure, it did not handle its fasync > >>> data pointer. Any ideas? Thanks. > >> Well, fasync doesn't need a cleanup usually. Do you have a proper > >> reproducer code? > > Sorry, I cannot reproduce it. I will apply your patch and test it. I > > will tell you the result whether it is okay a few days later. > > Thanks. > > > >> In anyway, try the patch below. I'm not sure whether this would help, > >> but if the path is via kill_fasync(), it'd be good to put in the > >> protected context. > >> > During the last few weeks, I have not seen the bug any more after > applying your patch. Thanks. Thanks, good to hear! The patch has been queued in for-next branch, so it'll be merged in 4.7. Takashi
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