syzbot


UBSAN: shift-out-of-bounds in __access_remote_vm

Status: fixed on 2023/02/24 13:50
Subsystems: ntfs3
[Documentation on labels]
Reported-by: syzbot+35b87c668935bb55e666@syzkaller.appspotmail.com
Fix commit: caad9dd8792a fs/ntfs3: Avoid UBSAN error on true_sectors_per_clst()
First crash: 640d, last: 639d
Cause bisection: introduced by (bisect log) :
commit 6e5be40d32fb1907285277c02e74493ed43d77fe
Author: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Date: Fri Aug 13 14:21:30 2021 +0000

  fs/ntfs3: Add NTFS3 in fs/Kconfig and fs/Makefile

Crash: UBSAN: shift-out-of-bounds in ntfs_fill_super (log)
Repro: C syz .config
  
Discussions (3)
Title Replies (including bot) Last reply
[PATCH] fs/ntfs3: fix negative shift size in true_sectors_per_clst() 13 (13) 2022/09/30 16:34
[PATCH] fs/ntfs3: Avoid UBSAN error on true_sectors_per_clst() 3 (3) 2022/09/30 15:53
[syzbot] UBSAN: shift-out-of-bounds in __access_remote_vm 0 (1) 2022/08/23 06:59

Sample crash report:
loop0: detected capacity change from 0 to 64
================================================================================
UBSAN: shift-out-of-bounds in fs/ntfs3/super.c:675:13
shift exponent -247 is negative
CPU: 0 PID: 3617 Comm: syz-executor807 Not tainted 6.0.0-rc1-next-20220819-syzkaller #0
BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:1521
in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 3617, name: syz-executor807
preempt_count: 0, expected: 0
RCU nest depth: 0, expected: 0
1 lock held by syz-executor807/3617:
 #0: ffff888022d380e0 (&type->s_umount_key#41/1){+.+.}-{3:3}, at: alloc_super+0x22e/0xb60 fs/super.c:228
irq event stamp: 4810
hardirqs last  enabled at (4809): [<ffffffff816199ce>] __up_console_sem+0xae/0xc0 kernel/printk/printk.c:264
hardirqs last disabled at (4810): [<ffffffff894c1738>] dump_stack_lvl+0x2e/0x134 lib/dump_stack.c:139
softirqs last  enabled at (4804): [<ffffffff81491a33>] invoke_softirq kernel/softirq.c:445 [inline]
softirqs last  enabled at (4804): [<ffffffff81491a33>] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:650
softirqs last disabled at (4789): [<ffffffff81491a33>] invoke_softirq kernel/softirq.c:445 [inline]
softirqs last disabled at (4789): [<ffffffff81491a33>] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:650
CPU: 0 PID: 3617 Comm: syz-executor807 Not tainted 6.0.0-rc1-next-20220819-syzkaller #0
syz-executor807[3617] cmdline: ./syz-executor807082514
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:122 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:140
 __might_resched.cold+0x222/0x26b kernel/sched/core.c:9896
 down_read_killable+0x75/0x490 kernel/locking/rwsem.c:1521
 mmap_read_lock_killable include/linux/mmap_lock.h:126 [inline]
 __access_remote_vm+0xac/0x6f0 mm/memory.c:5461
 get_mm_cmdline.part.0+0x217/0x620 fs/proc/base.c:299
 get_mm_cmdline fs/proc/base.c:367 [inline]
 get_task_cmdline_kernel+0x1d9/0x220 fs/proc/base.c:367
 dump_stack_print_cmdline.part.0+0x82/0x150 lib/dump_stack.c:61
 dump_stack_print_cmdline lib/dump_stack.c:89 [inline]
 dump_stack_print_info+0x185/0x190 lib/dump_stack.c:97
 __dump_stack lib/dump_stack.c:121 [inline]
 dump_stack_lvl+0xc1/0x134 lib/dump_stack.c:140
 ubsan_epilogue+0xb/0x50 lib/ubsan.c:151
 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x187 lib/ubsan.c:322
 parse_ntfs_boot_sector fs/ntfs/super.c:915 [inline]
 ntfs_fill_super.cold+0x147/0x56c fs/ntfs/super.c:2792
 get_tree_bdev+0x440/0x760 fs/super.c:1323
 vfs_get_tree+0x89/0x2f0 fs/super.c:1530
 do_new_mount fs/namespace.c:3040 [inline]
 path_mount+0x1326/0x1e20 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount fs/namespace.c:3568 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fcec358610a
Code: 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd5a5afbf8 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffd5a5afc50 RCX: 00007fcec358610a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffd5a5afc10
RBP: 00007ffd5a5afc10 R08: 00007ffd5a5afc50 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000286 R12: 0000000020000230
R13: 0000000000000003 R14: 0000000000000004 R15: 0000000000000002
 </TASK>
syz-executor807[3617] cmdline: ./syz-executor807082514
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:122 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:140
 ubsan_epilogue+0xb/0x50 lib/ubsan.c:151
 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x187 lib/ubsan.c:322
 parse_ntfs_boot_sector fs/ntfs/super.c:915 [inline]
 ntfs_fill_super.cold+0x147/0x56c fs/ntfs/super.c:2792
 get_tree_bdev+0x440/0x760 fs/super.c:1323
 vfs_get_tree+0x89/0x2f0 fs/super.c:1530
 do_new_mount fs/namespace.c:3040 [inline]
 path_mount+0x1326/0x1e20 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount fs/namespace.c:3568 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fcec358610a
Code: 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd5a5afbf8 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffd5a5afc50 RCX: 00007fcec358610a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffd5a5afc10
RBP: 00007ffd5a5afc10 R08: 00007ffd5a5afc50 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000286 R12: 0000000020000230
R13: 0000000000000003 R14: 0000000000000004 R15: 0000000000000002
 </TASK>
================================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2022/08/20 02:56 linux-next 8755ae45a9e8 26a13b38 .config strace log report syz C ci-upstream-linux-next-kasan-gce-root UBSAN: shift-out-of-bounds in __access_remote_vm
2022/08/20 02:42 linux-next 8755ae45a9e8 26a13b38 .config console log report info ci-upstream-linux-next-kasan-gce-root UBSAN: shift-out-of-bounds in __access_remote_vm
2022/08/19 06:53 linux-next 8755ae45a9e8 26a13b38 .config console log report info ci-upstream-linux-next-kasan-gce-root UBSAN: shift-out-of-bounds in __access_remote_vm
* Struck through repros no longer work on HEAD.