Re: KASAN: use-after-free Read in wait_for_completion

From: Dmitry Vyukov
Date: Wed Feb 20 2019 - 10:22:57 EST

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On Sun, Oct 21, 2018 at 11:40 AM syzbot
<syzbot+f25db12f1fd508824eac@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 270b77a0f30e Merge tag 'drm-fixes-2018-10-20-1' of git://a..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=152bb709400000
> kernel config: https://syzkaller.appspot.com/x/.config?x=b3f55cb3dfcc6c33
> dashboard link: https://syzkaller.appspot.com/bug?extid=f25db12f1fd508824eac
> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
>
> Unfortunately, I don't have any reproducer for this crash yet.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+f25db12f1fd508824eac@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ==================================================================
> BUG: KASAN: use-after-free in __lock_acquire+0x37c2/0x4ec0
> kernel/locking/lockdep.c:3290
> Read of size 8 at addr ffff8801d28a81a8 by task syz-executor4/12225

This seems to have been fixed by:

#syz fix: ucma: fix a use-after-free in ucma_resolve_ip()

So let's close the bug. Pile of neglected bug reports is not too useful.

> CPU: 1 PID: 12225 Comm: syz-executor4 Not tainted 4.19.0-rc8+ #72
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
> print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
> kasan_report_error mm/kasan/report.c:354 [inline]
> kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
> __lock_acquire+0x37c2/0x4ec0 kernel/locking/lockdep.c:3290
> lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900
> __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
> _raw_spin_lock_irq+0x61/0x80 kernel/locking/spinlock.c:160
> spin_lock_irq include/linux/spinlock.h:354 [inline]
> do_wait_for_common kernel/sched/completion.c:84 [inline]
> __wait_for_common kernel/sched/completion.c:104 [inline]
> wait_for_common kernel/sched/completion.c:115 [inline]
> wait_for_completion+0x436/0x8a0 kernel/sched/completion.c:136
> ucma_destroy_id+0x38a/0x550 drivers/infiniband/core/ucma.c:637
> ucma_write+0x365/0x460 drivers/infiniband/core/ucma.c:1689
> __vfs_write+0x119/0x9f0 fs/read_write.c:485
> vfs_write+0x1fc/0x560 fs/read_write.c:549
> ksys_write+0x101/0x260 fs/read_write.c:598
> __do_sys_write fs/read_write.c:610 [inline]
> __se_sys_write fs/read_write.c:607 [inline]
> __x64_sys_write+0x73/0xb0 fs/read_write.c:607
> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x457569
> Code: fd b3 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 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007fe8a3f8ec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457569
> RDX: 0000000000000018 RSI: 0000000020000280 RDI: 0000000000000005
> RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe8a3f8f6d4
> R13: 00000000004cb4f8 R14: 00000000004d8b68 R15: 00000000ffffffff
>
> Allocated by task 12210:
> save_stack+0x43/0xd0 mm/kasan/kasan.c:448
> set_track mm/kasan/kasan.c:460 [inline]
> kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
> kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620
> kmalloc include/linux/slab.h:513 [inline]
> kzalloc include/linux/slab.h:707 [inline]
> ucma_alloc_ctx+0xce/0x690 drivers/infiniband/core/ucma.c:209
> ucma_create_id+0x27d/0x990 drivers/infiniband/core/ucma.c:500
> ucma_write+0x365/0x460 drivers/infiniband/core/ucma.c:1689
> __vfs_write+0x119/0x9f0 fs/read_write.c:485
> vfs_write+0x1fc/0x560 fs/read_write.c:549
> ksys_write+0x101/0x260 fs/read_write.c:598
> __do_sys_write fs/read_write.c:610 [inline]
> __se_sys_write fs/read_write.c:607 [inline]
> __x64_sys_write+0x73/0xb0 fs/read_write.c:607
> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Freed by task 12210:
> save_stack+0x43/0xd0 mm/kasan/kasan.c:448
> set_track mm/kasan/kasan.c:460 [inline]
> __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
> kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
> __cache_free mm/slab.c:3498 [inline]
> kfree+0xcf/0x230 mm/slab.c:3813
> ucma_free_ctx+0x9e6/0xdb0 drivers/infiniband/core/ucma.c:599
> ucma_close+0x121/0x310 drivers/infiniband/core/ucma.c:1775
> __fput+0x385/0xa30 fs/file_table.c:278
> ____fput+0x15/0x20 fs/file_table.c:309
> task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
> get_signal+0x155e/0x1980 kernel/signal.c:2343
> do_signal+0x9c/0x21e0 arch/x86/kernel/signal.c:816
> exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162
> prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
> syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
> do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> The buggy address belongs to the object at ffff8801d28a8180
> which belongs to the cache kmalloc-256 of size 256
> The buggy address is located 40 bytes inside of
> 256-byte region [ffff8801d28a8180, ffff8801d28a8280)
> The buggy address belongs to the page:
> page:ffffea00074a2a00 count:1 mapcount:0 mapping:ffff8801da8007c0 index:0x0
> flags: 0x2fffc0000000100(slab)
> raw: 02fffc0000000100 ffffea000760b108 ffffea0007491148 ffff8801da8007c0
> raw: 0000000000000000 ffff8801d28a8040 000000010000000c 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
> ffff8801d28a8080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ffff8801d28a8100: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> > ffff8801d28a8180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ^
> ffff8801d28a8200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8801d28a8280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
> ==================================================================
>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> syzbot.
>
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Next message: Alan Stern: "Re: [RFC PATCH] tools/memory-model: Remove (dep ; rfi) from ppo"
Previous message: Chen-Yu Tsai: "Re: [PATCH] ARM: dts: sun7i: add pinctrl for missing uart mux options"
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