syzbot


KASAN: null-ptr-deref Write in get_block (2)

Status: fixed on 2023/09/28 17:51
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+aad58150cbc64ba41bdc@syzkaller.appspotmail.com
Fix commit: ea2b62f30589 fs/sysv: Null check to prevent null-ptr-deref bug
First crash: 374d, last: 336d
Cause bisection: failed (error log, bisect log)
  
Discussions (4)
Title Replies (including bot) Last reply
[PATCH AUTOSEL 6.4 05/16] fs/sysv: Null check to prevent null-ptr-deref bug 1 (1) 2023/07/02 19:38
[PATCH v3] fs/sysv: Null check to prevent null-ptr-deref bug 6 (6) 2023/06/01 07:55
[PATCH] Null check to prevent null-ptr-deref bug 2 (2) 2023/05/28 17:52
[syzbot] [fs?] KASAN: null-ptr-deref Write in get_block (2) 0 (1) 2023/05/22 22:36
Similar bugs (5)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 KASAN: null-ptr-deref Write in get_block origin:upstream missing-backport C done 4 297d 342d 3/3 fixed on 2023/10/02 12:03
upstream KASAN: null-ptr-deref Write in get_block fs C done 101 1414d 1527d 15/26 fixed on 2020/09/16 22:51
linux-5.15 KASAN: null-ptr-deref Write in get_block origin:upstream missing-backport C done 2 299d 345d 3/3 fixed on 2023/10/03 00:08
linux-4.14 BUG: unable to handle kernel NULL pointer dereference in get_block (2) C 1 451d 534d 0/1 upstream: reported C repro on 2022/12/09 08:52
upstream KASAN: slab-out-of-bounds Read in get_block (2) fs 1 504d 503d 0/26 auto-obsoleted due to no activity on 2023/05/09 01:15

Sample crash report:
memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=4998 'syz-executor295'
loop0: detected capacity change from 0 to 128
VFS: Found a Xenix FS (block size = 512) on device loop0
sysv_free_block: trying to free block not in datazone
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: null-ptr-deref in test_and_set_bit_lock include/asm-generic/bitops/instrumented-lock.h:57 [inline]
BUG: KASAN: null-ptr-deref in trylock_buffer include/linux/buffer_head.h:399 [inline]
BUG: KASAN: null-ptr-deref in lock_buffer include/linux/buffer_head.h:405 [inline]
BUG: KASAN: null-ptr-deref in alloc_branch fs/sysv/itree.c:148 [inline]
BUG: KASAN: null-ptr-deref in get_block+0x3e6/0x1580 fs/sysv/itree.c:251
Write of size 8 at addr 0000000000000000 by task syz-executor295/4998

CPU: 0 PID: 4998 Comm: syz-executor295 Not tainted 6.4.0-rc7-syzkaller-00194-g8a28a0b6f1a1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 print_report mm/kasan/report.c:465 [inline]
 kasan_report+0xec/0x130 mm/kasan/report.c:572
 check_region_inline mm/kasan/generic.c:181 [inline]
 kasan_check_range+0x141/0x190 mm/kasan/generic.c:187
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 test_and_set_bit_lock include/asm-generic/bitops/instrumented-lock.h:57 [inline]
 trylock_buffer include/linux/buffer_head.h:399 [inline]
 lock_buffer include/linux/buffer_head.h:405 [inline]
 alloc_branch fs/sysv/itree.c:148 [inline]
 get_block+0x3e6/0x1580 fs/sysv/itree.c:251
 __block_write_begin_int+0x3bd/0x14b0 fs/buffer.c:2064
 __block_write_begin fs/buffer.c:2114 [inline]
 block_write_begin+0xb9/0x4d0 fs/buffer.c:2175
 sysv_write_begin+0x31/0xd0 fs/sysv/itree.c:485
 generic_perform_write+0x256/0x570 mm/filemap.c:3929
 __generic_file_write_iter+0x2ae/0x500 mm/filemap.c:4057
 generic_file_write_iter+0xe3/0x350 mm/filemap.c:4089
 call_write_iter include/linux/fs.h:1868 [inline]
 do_iter_readv_writev+0x20b/0x3b0 fs/read_write.c:735
 do_iter_write+0x185/0x7e0 fs/read_write.c:860
 vfs_writev+0x1aa/0x670 fs/read_write.c:933
 do_pwritev fs/read_write.c:1030 [inline]
 __do_sys_pwritev fs/read_write.c:1077 [inline]
 __se_sys_pwritev fs/read_write.c:1072 [inline]
 __x64_sys_pwritev+0x22f/0x310 fs/read_write.c:1072
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f3830c5cb19
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 14 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd8b0f5988 EFLAGS: 00000246 ORIG_RAX: 0000000000000128
RAX: ffffffffffffffda RBX: 0031656c69662f2e RCX: 00007f3830c5cb19
RDX: 0000000000000005 RSI: 0000000020000480 RDI: 0000000000000004
RBP: 00007f3830c1c150 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000007fff R11: 0000000000000246 R12: 00007f3830c1c1e0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
==================================================================

Crashes (11):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/06/23 22:28 upstream 8a28a0b6f1a1 09ffe269 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-kasan-gce-root KASAN: null-ptr-deref Write in get_block
2023/05/18 22:41 upstream 4d6d4c7f541d 3bb7af1d .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs KASAN: null-ptr-deref Write in get_block
2023/06/25 16:02 upstream a92b7d26c743 09ffe269 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: null-ptr-deref Write in get_block
2023/06/25 15:58 upstream a92b7d26c743 79782afc .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: null-ptr-deref Write in get_block
2023/06/25 15:58 upstream a92b7d26c743 09ffe269 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: null-ptr-deref Write in get_block
2023/06/25 15:44 upstream a92b7d26c743 79782afc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: null-ptr-deref Write in get_block
2023/06/25 15:35 upstream a92b7d26c743 09ffe269 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: null-ptr-deref Write in get_block
2023/06/25 15:14 upstream a92b7d26c743 79782afc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: null-ptr-deref Write in get_block
2023/06/15 13:09 upstream b6dad5178cea 90d4044e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: null-ptr-deref Write in get_block
2023/05/18 22:22 upstream 4d6d4c7f541d 3bb7af1d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: null-ptr-deref Write in get_block
2023/06/25 15:53 upstream a92b7d26c743 79782afc .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 KASAN: null-ptr-deref Write in get_block
* Struck through repros no longer work on HEAD.