Messages in this thread | | | Date | Tue, 04 Jun 2019 13:07:05 -0700 | Subject | Re: possible deadlock in __do_page_fault (2) | From | syzbot <> |
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syzbot has found a reproducer for the following crash on:
HEAD commit: 56b697c6 Add linux-next specific files for 20190604 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=12d210d4a00000 kernel config: https://syzkaller.appspot.com/x/.config?x=4248d6bc70076f7d dashboard link: https://syzkaller.appspot.com/bug?extid=606e524a3ca9617cf8c0 compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17ddae0ea00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13e78f16a00000
The bug was bisected to:
commit 69d61f577d147b396be0991b2ac6f65057f7d445 Author: Mimi Zohar <zohar@linux.ibm.com> Date: Wed Apr 3 21:47:46 2019 +0000
ima: verify mprotect change is consistent with mmap policy
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16461c5aa00000 final crash: https://syzkaller.appspot.com/x/report.txt?x=15461c5aa00000 console output: https://syzkaller.appspot.com/x/log.txt?x=11461c5aa00000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+606e524a3ca9617cf8c0@syzkaller.appspotmail.com Fixes: 69d61f577d14 ("ima: verify mprotect change is consistent with mmap policy")
====================================================== WARNING: possible circular locking dependency detected 5.2.0-rc3-next-20190604 #8 Not tainted ------------------------------------------------------ syz-executor361/10886 is trying to acquire lock: 00000000c4471342 (&mm->mmap_sem#2){++++}, at: do_user_addr_fault arch/x86/mm/fault.c:1406 [inline] 00000000c4471342 (&mm->mmap_sem#2){++++}, at: __do_page_fault+0x9e9/0xda0 arch/x86/mm/fault.c:1521
but task is already holding lock: 000000009878d2b3 (&sb->s_type->i_mutex_key#10){+.+.}, at: inode_trylock include/linux/fs.h:798 [inline] 000000009878d2b3 (&sb->s_type->i_mutex_key#10){+.+.}, at: ext4_file_write_iter+0x246/0x1070 fs/ext4/file.c:232
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&sb->s_type->i_mutex_key#10){+.+.}: down_write+0x38/0xa0 kernel/locking/rwsem.c:66 inode_lock include/linux/fs.h:778 [inline] process_measurement+0x15ae/0x15e0 security/integrity/ima/ima_main.c:228 ima_file_mmap+0x11a/0x130 security/integrity/ima/ima_main.c:370 security_file_mprotect+0xd5/0x100 security/security.c:1426 do_mprotect_pkey+0x537/0xa30 mm/mprotect.c:550 __do_sys_mprotect mm/mprotect.c:582 [inline] __se_sys_mprotect mm/mprotect.c:579 [inline] __x64_sys_mprotect+0x78/0xb0 mm/mprotect.c:579 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #0 (&mm->mmap_sem#2){++++}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4300 down_read+0x3f/0x1e0 kernel/locking/rwsem.c:24 do_user_addr_fault arch/x86/mm/fault.c:1406 [inline] __do_page_fault+0x9e9/0xda0 arch/x86/mm/fault.c:1521 do_page_fault+0x71/0x57d arch/x86/mm/fault.c:1552 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1156 fault_in_pages_readable include/linux/pagemap.h:600 [inline] iov_iter_fault_in_readable+0x377/0x450 lib/iov_iter.c:426 generic_perform_write+0x186/0x520 mm/filemap.c:3197 __generic_file_write_iter+0x25e/0x630 mm/filemap.c:3336 ext4_file_write_iter+0x332/0x1070 fs/ext4/file.c:266 call_write_iter include/linux/fs.h:1870 [inline] new_sync_write+0x4d3/0x770 fs/read_write.c:483 __vfs_write+0xe1/0x110 fs/read_write.c:496 vfs_write+0x268/0x5d0 fs/read_write.c:558 ksys_write+0x14f/0x290 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:620 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#10); lock(&mm->mmap_sem#2); lock(&sb->s_type->i_mutex_key#10); lock(&mm->mmap_sem#2);
*** DEADLOCK ***
3 locks held by syz-executor361/10886: #0: 00000000b8e64295 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 #1: 00000000e032805f (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2836 [inline] #1: 00000000e032805f (sb_writers#3){.+.+}, at: vfs_write+0x485/0x5d0 fs/read_write.c:557 #2: 000000009878d2b3 (&sb->s_type->i_mutex_key#10){+.+.}, at: inode_trylock include/linux/fs.h:798 [inline] #2: 000000009878d2b3 (&sb->s_type->i_mutex_key#10){+.+.}, at: ext4_file_write_iter+0x246/0x1070 fs/ext4/file.c:232
stack backtrace: CPU: 0 PID: 10886 Comm: syz-executor361 Not tainted 5.2.0-rc3-next-20190604 #8 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+0x172/0x1f0 lib/dump_stack.c:113 print_circular_bug.cold+0x1cc/0x28f kernel/locking/lockdep.c:1566 check_prev_add kernel/locking/lockdep.c:2311 [inline] check_prevs_add kernel/locking/lockdep.c:2419 [inline] validate_chain kernel/locking/lockdep.c:2801 [inline] __lock_acquire+0x3755/0x5490 kernel/locking/lockdep.c:3790 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4300 down_read+0x3f/0x1e0 kernel/locking/rwsem.c:24 do_user_addr_fault arch/x86/mm/fault.c:1406 [inline] __do_page_fault+0x9e9/0xda0 arch/x86/mm/fault.c:1521 do_page_fault+0x71/0x57d arch/x86/mm/fault.c:1552 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1156 RIP: 0010:fault_in_pages_readable include/linux/pagemap.h:600 [inline] RIP: 0010:iov_iter_fault_in_readable+0x377/0x450 lib/iov_iter.c:426 Code: 89 f6 41 88 57 e0 e8 b8 dd 3c fe 45 85 f6 74 c1 e9 70 fe ff ff e8 29 dc 3c fe 0f 1f 00 0f ae e8 44 89 f0 48 8b 8d 68 ff ff ff <8a> 11 89 c3 0f 1f 00 41 88 57 d0 31 ff 89 de e8 85 dd 3c fe 85 db RSP: 0018:ffff88808ca6f918 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000200011ff RDX: 0000000000000000 RSI: ffffffff83341b37 RDI: 0000000000000007 RBP: ffff88808ca6f9b8 R08: ffff88809be68000 R09: ffff88809be688f8 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000001000 R13: 0000000000001000 R14: 0000000000000000 R15: ffff88808ca6f990 generic_perform_write+0x186/0x520 mm/filemap.c:3197 __generic_file_write_iter+0x25e/0x630 mm/filemap.c:3336 ext4_file_write_iter+0x332/0x1070 fs/ext4/file.c:266 call_write_iter include/linux/fs.h:1870 [inline] new_sync_write+0x4d3/0x770 fs/read_write.c:483 __vfs_write+0xe1/0x110 fs/read_write.c:496 vfs_write+0x268/0x5d0 fs/read_write.c:558 ksys_write+0x14f/0x290 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:620 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x446939 Code: e8 4c b4 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 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 0b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007effabbcdce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 0000000000446939 RDX: 000000000007fe00 RSI: 0000000020000200 RDI: 0000000000000006 RBP: 00000000006dbc30 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c R13: 00007ffd5dd15ddf R14: 00007effabbce9c0 R15: 20c49ba5e353f7cf
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