On Fri, Aug 10, 2018 at 6:18 PM Matthew Wilcox wrote: > > > This is another ashmem lockdep splat. Forwarding to the appropriate ashmem > people. Let's test Tetsuo's patch #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > On Fri, Aug 10, 2018 at 04:59:02AM -0700, syzbot wrote: > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit: 4110b42356f3 Add linux-next specific files for 20180810 > > git tree: linux-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=1411d6e2400000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=1d80606e3795a4f5 > > dashboard link: https://syzkaller.appspot.com/bug?extid=4b8b031b89e6b96c4b2e > > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=175052f8400000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11873622400000 > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+4b8b031b89e6b96c4b2e@syzkaller.appspotmail.com > > > > random: sshd: uninitialized urandom read (32 bytes read) > > random: sshd: uninitialized urandom read (32 bytes read) > > random: sshd: uninitialized urandom read (32 bytes read) > > > > ====================================================== > > WARNING: possible circular locking dependency detected > > 4.18.0-rc8-next-20180810+ #36 Not tainted > > ------------------------------------------------------ > > syz-executor900/4483 is trying to acquire lock: > > 00000000d2bfc8fe (&sb->s_type->i_mutex_key#9){++++}, at: inode_lock > > include/linux/fs.h:765 [inline] > > 00000000d2bfc8fe (&sb->s_type->i_mutex_key#9){++++}, at: > > shmem_fallocate+0x18b/0x12e0 mm/shmem.c:2602 > > > > but task is already holding lock: > > 0000000025208078 (ashmem_mutex){+.+.}, at: ashmem_shrink_scan+0xb4/0x630 > > drivers/staging/android/ashmem.c:448 > > > > which lock already depends on the new lock. > > > > > > the existing dependency chain (in reverse order) is: > > > > -> #2 (ashmem_mutex){+.+.}: > > __mutex_lock_common kernel/locking/mutex.c:925 [inline] > > __mutex_lock+0x171/0x1700 kernel/locking/mutex.c:1073 > > mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088 > > ashmem_mmap+0x55/0x520 drivers/staging/android/ashmem.c:361 > > call_mmap include/linux/fs.h:1844 [inline] > > mmap_region+0xf27/0x1c50 mm/mmap.c:1762 > > do_mmap+0xa10/0x1220 mm/mmap.c:1535 > > do_mmap_pgoff include/linux/mm.h:2298 [inline] > > vm_mmap_pgoff+0x213/0x2c0 mm/util.c:357 > > ksys_mmap_pgoff+0x4da/0x660 mm/mmap.c:1585 > > __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] > > __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline] > > __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91 > > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > -> #1 (&mm->mmap_sem){++++}: > > __might_fault+0x155/0x1e0 mm/memory.c:4568 > > _copy_to_user+0x30/0x110 lib/usercopy.c:25 > > copy_to_user include/linux/uaccess.h:155 [inline] > > filldir+0x1ea/0x3a0 fs/readdir.c:196 > > dir_emit_dot include/linux/fs.h:3464 [inline] > > dir_emit_dots include/linux/fs.h:3475 [inline] > > dcache_readdir+0x13a/0x620 fs/libfs.c:193 > > iterate_dir+0x48b/0x5d0 fs/readdir.c:51 > > __do_sys_getdents fs/readdir.c:231 [inline] > > __se_sys_getdents fs/readdir.c:212 [inline] > > __x64_sys_getdents+0x29f/0x510 fs/readdir.c:212 > > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > -> #0 (&sb->s_type->i_mutex_key#9){++++}: > > lock_acquire+0x1e4/0x540 kernel/locking/lockdep.c:3924 > > down_write+0x8f/0x130 kernel/locking/rwsem.c:70 > > inode_lock include/linux/fs.h:765 [inline] > > shmem_fallocate+0x18b/0x12e0 mm/shmem.c:2602 > > ashmem_shrink_scan+0x236/0x630 drivers/staging/android/ashmem.c:455 > > ashmem_ioctl+0x3ae/0x13a0 drivers/staging/android/ashmem.c:797 > > vfs_ioctl fs/ioctl.c:46 [inline] > > file_ioctl fs/ioctl.c:501 [inline] > > do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 > > ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 > > __do_sys_ioctl fs/ioctl.c:709 [inline] > > __se_sys_ioctl fs/ioctl.c:707 [inline] > > __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 > > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > other info that might help us debug this: > > > > Chain exists of: > > &sb->s_type->i_mutex_key#9 --> &mm->mmap_sem --> ashmem_mutex > > > > Possible unsafe locking scenario: > > > > CPU0 CPU1 > > ---- ---- > > lock(ashmem_mutex); > > lock(&mm->mmap_sem); > > lock(ashmem_mutex); > > lock(&sb->s_type->i_mutex_key#9); > > > > *** DEADLOCK *** > > > > 1 lock held by syz-executor900/4483: > > #0: 0000000025208078 (ashmem_mutex){+.+.}, at: > > ashmem_shrink_scan+0xb4/0x630 drivers/staging/android/ashmem.c:448 > > > > stack backtrace: > > CPU: 1 PID: 4483 Comm: syz-executor900 Not tainted 4.18.0-rc8-next-20180810+ > > #36 > > 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+0x1c9/0x2b4 lib/dump_stack.c:113 > > print_circular_bug.isra.37.cold.58+0x1bd/0x27d > > kernel/locking/lockdep.c:1227 > > check_prev_add kernel/locking/lockdep.c:1867 [inline] > > check_prevs_add kernel/locking/lockdep.c:1980 [inline] > > validate_chain kernel/locking/lockdep.c:2421 [inline] > > __lock_acquire+0x3449/0x5020 kernel/locking/lockdep.c:3435 > > lock_acquire+0x1e4/0x540 kernel/locking/lockdep.c:3924 > > down_write+0x8f/0x130 kernel/locking/rwsem.c:70 > > inode_lock include/linux/fs.h:765 [inline] > > shmem_fallocate+0x18b/0x12e0 mm/shmem.c:2602 > > ashmem_shrink_scan+0x236/0x630 drivers/staging/android/ashmem.c:455 > > ashmem_ioctl+0x3ae/0x13a0 drivers/staging/android/ashmem.c:797 > > vfs_ioctl fs/ioctl.c:46 [inline] > > file_ioctl fs/ioctl.c:501 [inline] > > do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 > > ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 > > __do_sys_ioctl fs/ioctl.c:709 [inline] > > __se_sys_ioctl fs/ioctl.c:707 [inline] > > __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 > > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > RIP: 0033:0x440099 > > Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00 > > RSP: 002b:00007fff3613dbf8 EFLAGS: 00000217 ORIG_RAX: 0000000000000010 > > RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440099 > > RDX: 00000 > > > > > > --- > > 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@googlegroups.com. > > > > syzbot will keep track of this bug report. See: > > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with > > syzbot. > > syzbot can test patches for this bug, for details see: > > https://goo.gl/tpsmEJ#testing-patches > > > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20180810161848.GB16533%40bombadil.infradead.org. > For more options, visit https://groups.google.com/d/optout.